Conservapedia - User contributions [en]

User:BMcP

2010-02-11T16:59:33Z

BMcP:

{{userboxtop|A Little About Me}}
{{User Evo}}
{{User bigbang}}
{{user evolutionScience}}
{{User Constitution}}
{{User progun}}
{{User free speech}}
{{User moderatecapitalist}}
{{User noforcedreligion}}
{{Userbox |border-c=#000 |border-s=1 |id-c=#fff |id-s=12 |id-fc=#000 |info-c=#039 |info-s=8 |info-fc=#fff |id=Ag |info=This user is agnostic towards the supernatural.}}
{{Userbox |border-c=#000 |border-s=1 |id-c=#fff |id-s=12 |id-fc=#000 |info-c=#039 |info-s=8 |info-fc=#fff |id=Sk |info=This user is a skeptic.}}
{{User Geek}}
{{User comp-5}}
{{User cows tasty}}
{{userboxbottom}}

==Final Message==

With initial reservation I have decided that this project is no wonder worth the effort to contribute to. I came here with the hope of finding a place where I could create a reservoir of knowledge in the areas this place was lacking, specifically in my field of knowledge, astronomy, a field that I contribute to out of sheer joy and the hopes my little contribute will somehow add to the pool of knowledge. OF course I will continue to do that but not here.

To [[User:Karajou|Karajou]], thank you for all the assistance and help with templates and images, it was most appreciated.

To [[User:JacobB|JacobB]], I held hope that our compromise would allow astronomy articles on this site to go forward, but duke of this fiefdom has decreed there will be no compromise and that even having an "Old Universe View" is forbidden. I know we had our disagreements, many of them, but I hold no ill will or bad feelings towards you. Good luck on your endeavors.

To the other admins, thanks for the help on occasion with stuff. All I can say is I know some of you are not as ideological as you appear here but must maintain that facade in order to stay in the good graces of the dictator at the top. I wish you luck and hopefully something better.

To everyone else who helped with grammar and information, thank you.

I feel that I need to exit because any scientific knowledge, facts, or subjects, no matter how well cited, or explained will always be subject to censorship for the sake of the closed-minded dogma of the owner of this site. Be warned, it doesn't matter how well researched your articles are, or how many science peer reviewed papers, if it does conform to ideological and religious views of the ruler of this site, it doesn't stay and you have to fight for every scientific fact you note.

I understand why Young Earth Creationists had reservations over the universe's age even if I didn't agree, I could at least understand, but the idea that distance, which is easily measured and can be repeated over and over, is somehow forbidden if it exceeds 6000 light years is absurd. Most creationists even fully acknowledge the size of the universe.

I blame no one, neither users nor the other admins, and even though the ideological demands by the top will demand and force many here to now condemn me using any number of slander, I will hold no ill-will against any of you, I know it is done to projects yourselves and your contributions here. I just ask, is it worth it? If so, work to change this project to something that contributes to knowledge.

As for Conservapedia, it is not a meritocracy but an oligarchy of favoritism based on kissing the toes of the owner. It will continue to limber on, but despite all the claims to the contrary and support from insignificant Youtube users, it will not challenge Wikipedia because it is not taken seriously by people or conservatism at large. Contemplate why, if not, you will live in obscurity, hidden behind Wikipedia's immense shadow, only to occasionally come out to the public eye only for the sake derision and lutz. Most of this projects hits are from those to watch to laugh, that should tell you something.

Good luck to you all, remember the universe is a beautiful and magnificent wonder full of mystery and awe, really look at it, learn about it, do not let religious ideology hold you back from discovering how amazing everything really is. Life is too precious and we get only one shot.

-- BMcP

User:BMcP

2010-02-11T16:57:36Z

BMcP:

{{userboxtop|A Little About Me}}
{{User Evo}}
{{User bigbang}}
{{user evolutionScience}}
{{User Constitution}}
{{User progun}}
{{User free speech}}
{{User moderatecapitalist}}
{{User noforcedreligion}}
{{Userbox |border-c=#000 |border-s=1 |id-c=#fff |id-s=12 |id-fc=#000 |info-c=#039 |info-s=8 |info-fc=#fff |id=Ag |info=This user is agnostic towards the supernatural.}}
{{Userbox |border-c=#000 |border-s=1 |id-c=#fff |id-s=12 |id-fc=#000 |info-c=#039 |info-s=8 |info-fc=#fff |id=Sk |info=This user is a skeptic.}}
{{User Geek}}
{{User comp-5}}
{{User cows tasty}}
{{userboxbottom}}

==Final Message==

With initial reservation I have decided that this project is no wonder worth the effort to contribute to. I came here with the hope of finding a place where I could create a reservoir of knowledge in the areas this place was lacking, specifically in my field of knowledge, astronomy, a field that I contribute to out of sheer joy and the hopes my little contribute will somehow add to the pool of knowledge. OF course I will continue to do that but not here.

To [[User:Karajou|Karajou]], thank you for all the assistance and help with templates and images, it was most appreciated.

To [[User:JacobB|JacobB]], I held hope that our compromise would allow astronomy articles on this site to go forward, but duke of this fiefdom has decreed there will be no compromise and that even having an "Old Universe View" is forbidden. I know we had our disagreements, many of them, but I hold no ill will or bad feelings towards you. Good luck on your endeavors.

To the other admins, thanks for the help on occasion with stuff. All I can say is I know some of you are not as ideological as you appear here but must maintain that facade in order to stay in the good graces of the dictator at the top. I wish you luck and hopefully something better.

To everyone else who helped with grammar and information, thank you.

I feel that I need to exit because any scientific knowledge, facts, or subjects, no matter how well cited, or explained will always be subject to censorship for the sake of the closed-minded dogma of the owner of this site. Be warned, it doesn't matter how well researched your articles are, or how many science peer reviewed papers, if it does conform to ideological and religious views of the ruler of this site, it doesn't stay and you have to fight for every scientific fact you note.

I understand why Young Earth Creationists had reservations over the universe's age even if I didn't agree, I could at least understand, but the idea that distance, which is easily measured and can be repeated over and over, is somehow forbidden if it exceeds 6000 light years is absurd. Most creationists even fully acknowledge the size of the universe.

I blame no one, neither users nor the other admins, and even though the ideological demands by the top will demand and force many here to now condemn me using any number of slander, I will hold no ill-will against any of you, I know it is done to projects yourselves and your contributions here. I just ask, is it worth it? If so, work to change this project to something that contributes to knowledge.

As for Conservapedia, it is not a meritocracy but an oligarchy of favoritism based on kissing the toes of the owner. It will continue to limber on, but despite all the claims to the contrary and support from insignificant Youtube users, it will not challenge Wikipedia because it is not taken seriously by people or conservatism at large. Contemplate why, if not, you will live in obscurity, hidden behind Wikipedia's immense shadow, only to occasionally come out to the public eye only for the sake derision and lutz. Most of this projects hits are from those to watch to laugh, that should tell you something.

Good luck and really think about it, so many of you have great potential, do not waste it.

-- BMcP

User:BMcP

2010-02-11T16:51:15Z

BMcP:

{{userboxtop|A Little About Me}}
{{User Evo}}
{{User bigbang}}
{{user evolutionScience}}
{{User Constitution}}
{{User progun}}
{{User free speech}}
{{User moderatecapitalist}}
{{User noforcedreligion}}
{{Userbox |border-c=#000 |border-s=1 |id-c=#fff |id-s=12 |id-fc=#000 |info-c=#039 |info-s=8 |info-fc=#fff |id=Ag |info=This user is agnostic towards the supernatural.}}
{{Userbox |border-c=#000 |border-s=1 |id-c=#fff |id-s=12 |id-fc=#000 |info-c=#039 |info-s=8 |info-fc=#fff |id=Sk |info=This user is a skeptic.}}
{{User Geek}}
{{User comp-5}}
{{User cows tasty}}
{{userboxbottom}}

==Final Message==

With initial reservation I have decided that this project is no wonder worth the effort to contribute to. I came here with the hope of finding a place where I could create a reservoir of knowledge in the areas this place was lacking, specifically in my field of knowledge, astronomy, a field that I contribute to out of sheer joy and the hopes my little contribute will somehow add to the pool of knowledge. OF course I will continue to do that but not here.

To [[Karajou]], thank you for all the assistance and help with templates and images, it was most appreciated.

To [[JacobB]], I held hope that our compromise would allow astronomy articles on this site to go forward, but duke of this fiefdom has decreed there will be no compromise and that even having an "Old Universe View" is forbidden. I know we had our disagreements, many of them, but I hold no ill will or bad feelings towards you. Good luck on your endeavors.

To the other admins, thanks for the help on occasion with stuff. All I can say is I know some of you are not as ideological as you appear here but must maintain that facade in order to stay in the good graces of the dictator at the top. I wish you luck and hopefully something better.

To everyone else who helped with grammar and information, thank you.

I feel that I need to exit because any scientific knowledge, facts, or subjects, no matter how well cited, or explained will always be subject to censorship for the sake of the closed-minded dogma of the owner of this site. Be warned, it doesn't matter how well researched your articles are, or how many science peer reviewed papers, if it does conform to ideological and religious views of the ruler of this site, it doesn't stay and you have to fight for every scientific fact you note.

I understand why Young Earth Creationists had reservations over the universe's age even if I didn't agree, I could at least understand, but the idea that distance, which is easily measured and can be repeated over and over, is somehow forbidden if it exceeds 6000 light years is absurd. Most creationists even fully acknowledge the size of the universe.

I blame no one, neither users nor the other admins, and even though the ideological demands by the top will demand and force many here to now condemn me using any number of slander, I will hold no ill-will against any of you, I know it is done to projects yourselves and your contributions here. I just ask, is it worth it? If so, work to change this project to something that contributes to knowledge.

As for Conservapedia, it is not a meritocracy but an oligarchy of favoritism based on kissing the toes of the owner. It will continue to limber on, but despite all the claims to the contrary and support from insignificant Youtube users, it will not challenge Wikipedia because it is not taken seriously by people or conservatism at large. Contemplate why, if not, you will live in obscurity, hidden behind Wikipedia's immense shadow, only to occasionally come out to the public eye only for the sake derision and lutz. Most of this projects hits are from those to watch to laugh, that should tell you something.

Good luck and really think about it, so many of you have great potential, do not waste it.

-- BMcP

User talk:JacobB

2010-02-11T16:51:01Z

BMcP:

For older discussions, see the archives: [[User talk:JacobB/Archive 1|1]], [[User talk:JacobB/Archive 2|2]]



==rant #50==
Hello, JacobB, my name is WilsonB. And while we're both COMMITTED Catholics, I'm sorry to tell you that I have a beef with you over some actions you took over my work.
A few minutes ago, you blocked my editing of this encyclopedia's page of the movie adaptation of Mulan. You blocked out my attempt to show that while it may be feministic and occultic, it may also be conservative, too. Now, I will, from now on, no longer allow anything from my blog to appear on any page or my opinion for that matter. But I am upset for a few reasons.
I find the fact that no suggestion of conservative messages in the movie in question, yet suggestion that it's occultic, on the page in question is completely disturbing for several reasons. In my opinion, it is downright repulsive to offer evidence to suggest that "Mulan" is occultic without any evidence at all. By that I mean that there are no sources to back it up! Where are the references? If this is fact, and not opinion, that "Mulan" is occultic, don't we need to go out to a database of some kind and cite sources? Isn't that how all encyclopedia pages are done online? Yes, the idea that the film in question is occultic can still stand, but only if sources are cited next time around.
I mean, I have been a good conservative all my life, and "Mulan", in fact, was my introduction to conservative thought. In this case, it introduced me to the fact that, despite the leftist delusion of "War Is Not The Answer", we really do need the "Mulans" of our time. That is, we need men and women who are willing to go out and serve their country and die if necessary. "Mulan", if properly viewed, can be an excellent way of teaching that to children. So forget the occult and feminism. (We, of course, have our own "feminists", even thought they're not really that, such as Sarah Palin.) Therefore, I just find it troubling that personal opinion would be put on in onw scenario and ignored in another. I mean, just imagine what would happen if someone on Wikipedia called "Mulan" occultic to produce another side. Jimbo's in-box would start lighting up like a Christmas Tree-oh, wait, maybe I shouldn't say that; it might offend someone.
Remember, I am not mad at you for ruining my work. I'm just livid about this. If I could bring you to my house one day, get the film on DVD, and bring you to watch it with me, I would. But since I don't have a DVD copy, and since I'm probably not going to give complete strangers my home address to bring them here, all I'll just do is tell you of what needs to be done for this encyclopedia to be both conservative AND based in a non-partisan format. Again, "Mulan" is not occultic, in my opinion, but you're free to decide.
Sincerely,
[[User: WilsonB]]
:I'm quite capable of reading your talk page, there was no need to reproduce this here. Apparently, you are not able to read the your talk page, as I gave a calm and rational response there, in which I explained I had never seen Mulan and don't care in the slightest what content you wish to add to that page, though others might.
:I even assumed the issue had been cleared up when an Admin came to offer his services to back me up, I said, no, not necessary, because I assumed you were rational enough to read my response. I will not make this mistaken assumption with you in the future. Take some time to cool your head. [[User:JacobB|JacobB]]

== Math lectures ==

Just fantastically cool! Just wondering, should the derivative of d/dx log(x) = x^-1 in 3.1 read d/dx ln(x)? Or is log(x) always assumed to be log''e''(x) unless specified or something? [[User:DouglasA|DouglasA]] 11:50, 4 January 2010 (EST)

:Not to butt in ahead of JacobB, but it was pretty much assumed in the calc courses I've taken. It might be good to add a note to that effect, though. --[[User:EvanW|EvanW]] 11:52, 4 January 2010 (EST)
::Okay, good to know. [[User:DouglasA|DouglasA]] 11:53, 4 January 2010 (EST)
My experience is that mathematicians use log or ln ("lawn") for natural logs, since we never use log10 at all, and physicists use ln for natural log and log for log10.
It would probably be best to use ln for natural log to avoid confusion - my consistent use of log is a result of my long-time use of it for natural log, and the thing is, it's too ingrained of a habit to break now, so I'm probably going to keep using log. If it matters so much to somebody, they're welcome to change it. [[User:JacobB|JacobB]] 19:33, 4 January 2010 (EST)

==Welcoming new users==

I've been inactive for a while, so I may have missed this: is it a custom around here to welcome new users by placing a template on their user page? --[[User:Ed Poor|Ed Poor]] [[User talk:Ed Poor|Talk]] 19:48, 4 January 2010 (EST)
:TK does it, but if this is only for admins to do, I'll stop. [[User:JacobB|JacobB]] 19:55, 4 January 2010 (EST)

==Write for the educated layman==

Important instructions for you are [[User_talk:JacobB/Banach-Tarski_Paradox#Jargon|here]]. Please read them, and submit a [[writing plan]]. --[[User:Ed Poor|Ed Poor]] [[User talk:Ed Poor|Talk]] 11:20, 8 January 2010 (EST)

== Multivariable Calc course ==

Jacob, this is very doable. I have nearly 50 students in my Economics course and nearly all stuck with it. It's college-level material and many of them are taking the [[CLEP]] to earn credit.

We can do the [[Multivariable calculus]] course and I developed that entry as an overview. Please feel free to use or link as you think best to your developing material.--[[User:Aschlafly|Andy Schlafly]] 20:34, 9 January 2010 (EST)
:That's great! I'll make sure to hit all of that material in the lectures. Like I've said, I'm incredibly busy at work this week and I'm taking it home with me, but next week I'll have four days to just work on calc lectures. Expect a lot of material to go up Tues-Fri! [[User:JacobB|JacobB]] 20:42, 9 January 2010 (EST)

::The Economics course that just completed is a successful model. But [[Multivariable calculus]] may be more advanced than anything the [[CLEP]] offers! No problem ... our students are doing this to learn, not merely to impress institutions. The reality is that a conservative approach is far superior for learning.--[[User:Aschlafly|Andy Schlafly]] 23:27, 10 January 2010 (EST)

:::I'm looking at the CLEP exams right now, and once I finish these Multivariable Calc lectures, I don't see any reason why I can't put up lectures which would prepare the student for [http://www.collegeboard.com/student/testing/clep/ex_cm.html this exam] and [http://www.collegeboard.com/student/testing/clep/ex_ca.html this exam]. [[User:JacobB|JacobB]] 23:45, 10 January 2010 (EST)

== Please check your email, I am awaiting a response.. ==

Thanks! --<big>[[User:TK|'''ṬK''']]</big>/Admin[[User_Talk:TK|/Talk]] 01:48, 10 January 2010 (EST)

== Riemann picture ==

I tried linking the [[Riemann Integral]] page to the new picture, and it doesn't seem to work. I tried both "File:Riemannsums.gif" and "Image:Riemannsums.gif". Can you try to see if you can use your extra privileges (or extra intelligence, or extra knowledge, or extra common sense, or whatever it takes :-) to fix this? [[User:SamHB|SamHB]] 23:34, 18 January 2010 (EST)

==Best of luck==

I held hope that our compromise would allow astronomy articles on this site to go forward, but duke of this fiefdom has decreed there will be no compromise and that even having an "Old Universe View" is forbidden. I know we had our disagreements, many of them, but I hold no ill will or bad feelings towards you. Good luck on your endeavors and if you ever wish to say hello by email, please feel free. --[[User:BMcP|BMcP]] 11:51, 11 February 2010 (EST)

Talk:Andromeda galaxy

2010-02-11T16:50:51Z

BMcP: /* Stop.. wait */

== Disclaimer ==

Perhaps at the top of each astronomy article we can put a disclaimer like "This article assumes a universe that is approximately 13,7 billion years old. This is just a theory and in no way has been proven." That way we can keep in the science. [[User:DaneW|DaneW]] 00:15, 11 February 2010 (EST)

:How about you actually read the comment I left the other day on your talk page? I find you deceitful, stating one purpose for being here, and editing everything but. Did you follow the links to the other pages linked to the Commandments? The are adjunct to them, as clearly stated on their page. --<big>[[User:TK|'''ṬK''']]</big>/Admin[[User_Talk:TK|/Talk]] 00:32, 11 February 2010 (EST)

::I've had a dispute with another editor here, BMcP, regarding this. The compromise we reached is that material which states or implies the universe is millions of years old or older should be placed in a "Old Universe View" section, while material that states or implies that universe is thousands of years old or younger should be placed in a "Young Universe Section." This agreement seems to me to satisfy all parties. [[User:JacobB|JacobB]] 02:19, 11 February 2010 (EST)

:::I don't think "compromises" as to the deceit of an editor here are within my purview, Jacob...that would be between the user and God. What is within my purview is the decision as to if CP should be an enabler for his deceit. Thanks for the suggestion, but I am certain I have the ability to decide this. ;-) --<big>[[User:TK|'''ṬK''']]</big>/Admin[[User_Talk:TK|/Talk]] 04:52, 11 February 2010 (EST)

:::: Whoa, okay TK that was uncalled for. There is one small area that references to age in this article: "''From this the astronomers calcuated that the various stars of Andromeda's halo vary in age from 6 to 13 billion years, a much wider range then the halo population of the Milky Way that mostly consists of metal-poor stars some 11-13 billion years old.<ref>http://www.skyandtelescope.com/news/3307606.html?page=1&c=y</ref>'' ".

:::: That was placed in '''before''' the compromise JacobB and I reached in regards to talking about age of the universe and how they should be placed into an "Old Universe View" and "Young Universe View" section. No one just got around to this article yet in light of that compromise. No one is trying to be deceitful, and I resent the implication, what is worse is you know how to contact me directly live, you could have asked instead of assumed I am trying something "deceitful". --[[User:BMcP|BMcP]] 08:29, 11 February 2010 (EST)

:::::I was addressing Jacob's and DaneW's comments here, BMcP, and nothing else. --<big>[[User:TK|'''ṬK''']]</big>/Admin[[User_Talk:TK|/Talk]] 08:40, 11 February 2010 (EST)

::::::Then I apologize. --[[User:BMcP|BMcP]] 08:51, 11 February 2010 (EST)
Atcually, TK, I was trying to tell Dane why his idea was a bad one, ie, support you. [[User:JacobB|JacobB]] 11:45, 11 February 2010 (EST)

'''A disclaimer doesn't resolve logical flaws or over-reliance on assumptions or atheism-pushing. I found it astounding how much this entry pushed an old universe, atheistic ideology for no apparent scientific purpose.'''

'''I would oppose a disclaimer that said, for example, "this entry assumes that greenhouse gases are causing the world to become dangerously warmer."--[[User:Aschlafly|Andy Schlafly]] 06:26, 11 February 2010 (EST)'''

== Stop.. wait==

Why is distance and size information being ripped out of this article, especially since it is virtually all cited? Why isn't it discussed first in the talk section here? What is disputed about distance? Distance to extra-galactic objects are not just guessed at and it doesn't imply age, it just implies distance. I mean how small do people think the universe is? As far as I know, but creationists and non-creationists agree the universe is very large and most galaxies are millions or billions of light years away. --[[User:BMcP|BMcP]] 08:29, 11 February 2010 (EST)

:BMcP, I explained this on your talk page many days ago, without a satisfactory response. We don't simply repeat, robot-like, the implausible or illogical claims of atheists here. You're in the wrong place for that. Mindless repetition of [[liberal]] claims may work on Wikipedia, but not here.

:An example is the claim that you've just reinserted that this galaxy will collide with Earth in many billions of years. It's a ludicrous, non-scientific assertion that is simply designed to pry people from the Bible and from God.

:I've begged you to reconsider the liberal assumptions with an open mind. I've begged you to open the Bible and spend some meaningful time reading it with an open mind. But I can't and wouldn't force you to do either. What I will do is keep the atheistic nonsense off this site, unless you want to post it under a new entry entitled "liberal claims lacking in scientific verification."

::The radial velocity of the Andromeda galaxy with respect to the Milky Way can be measured by examining the Doppler shift of spectral lines from stars in the galaxy. Using this the Andromeda Galaxy is approaching the Sun at about 100 to 140 kilometers per second.[http://www.space.com/scienceastronomy/astronomy/galaxy_collides_020507-1.html] We can then estimate how long it would be before the galaxies meet up using math. That is how we get the estimate of 2.5 billion or so years. I will however concede that the collision is uncertain because the two galaxies may move past each other instead because we cannot exactly measure Andromeda's transverse velocity. Because of that, I will change the text about the galaxies colliding to being uncertain. Is this acceptable?

:::The claim is completely unverifiable. It's absurd even to contemplate whether the universe would exist so far into the future, not to mention the assumptions you're making about physical constants.

:::BMcP, I'm not going to spend all day urging you again and again to open your mind and confront the liberal assumptions. Open your mind or go edit on another site. Atheistic Wikipedia might welcome the unverified, pro-liberal junk science.--[[User:Aschlafly|Andy Schlafly]] 10:32, 11 February 2010 (EST)

::::Measuring the galaxy's distance, velocity, and size is cited over and over, I urge you to actually read the science papers linked. As for its approach, you can measure that using the Doppler Effect, if you do not understand this effect, there are articles explaining how it works. You can even measure yourself using the right equipment. My only assumption is the raw data isn't fudged and if it is, any measurement will soon show that, so I am confident in the data. --[[User:BMcP|BMcP]] 11:50, 11 February 2010 (EST)

Talk:Andromeda galaxy

2010-02-11T15:14:04Z

BMcP: /* Stop.. wait */

== Disclaimer ==

Perhaps at the top of each astronomy article we can put a disclaimer like "This article assumes a universe that is approximately 13,7 billion years old. This is just a theory and in no way has been proven." That way we can keep in the science. [[User:DaneW|DaneW]] 00:15, 11 February 2010 (EST)

:How about you actually read the comment I left the other day on your talk page? I find you deceitful, stating one purpose for being here, and editing everything but. Did you follow the links to the other pages linked to the Commandments? The are adjunct to them, as clearly stated on their page. --<big>[[User:TK|'''ṬK''']]</big>/Admin[[User_Talk:TK|/Talk]] 00:32, 11 February 2010 (EST)

::I've had a dispute with another editor here, BMcP, regarding this. The compromise we reached is that material which states or implies the universe is millions of years old or older should be placed in a "Old Universe View" section, while material that states or implies that universe is thousands of years old or younger should be placed in a "Young Universe Section." This agreement seems to me to satisfy all parties. [[User:JacobB|JacobB]] 02:19, 11 February 2010 (EST)

:::I don't think "compromises" as to the deceit of an editor here are within my purview, Jacob...that would be between the user and God. What is within my purview is the decision as to if CP should be an enabler for his deceit. Thanks for the suggestion, but I am certain I have the ability to decide this. ;-) --<big>[[User:TK|'''ṬK''']]</big>/Admin[[User_Talk:TK|/Talk]] 04:52, 11 February 2010 (EST)

:::: Whoa, okay TK that was uncalled for. There is one small area that references to age in this article: "''From this the astronomers calcuated that the various stars of Andromeda's halo vary in age from 6 to 13 billion years, a much wider range then the halo population of the Milky Way that mostly consists of metal-poor stars some 11-13 billion years old.<ref>http://www.skyandtelescope.com/news/3307606.html?page=1&c=y</ref>'' ".

:::: That was placed in '''before''' the compromise JacobB and I reached in regards to talking about age of the universe and how they should be placed into an "Old Universe View" and "Young Universe View" section. No one just got around to this article yet in light of that compromise. No one is trying to be deceitful, and I resent the implication, what is worse is you know how to contact me directly live, you could have asked instead of assumed I am trying something "deceitful". --[[User:BMcP|BMcP]] 08:29, 11 February 2010 (EST)

:::::I was addressing Jacob's and DaneW's comments here, BMcP, and nothing else. --<big>[[User:TK|'''ṬK''']]</big>/Admin[[User_Talk:TK|/Talk]] 08:40, 11 February 2010 (EST)

::::::Then I apologize. --[[User:BMcP|BMcP]] 08:51, 11 February 2010 (EST)

'''A disclaimer doesn't resolve logical flaws or over-reliance on assumptions or atheism-pushing. I found it astounding how much this entry pushed an old universe, atheistic ideology for no apparent scientific purpose.'''

'''I would oppose a disclaimer that said, for example, "this entry assumes that greenhouse gases are causing the world to become dangerously warmer."--[[User:Aschlafly|Andy Schlafly]] 06:26, 11 February 2010 (EST)'''

== Stop.. wait==

Why is distance and size information being ripped out of this article, especially since it is virtually all cited? Why isn't it discussed first in the talk section here? What is disputed about distance? Distance to extra-galactic objects are not just guessed at and it doesn't imply age, it just implies distance. I mean how small do people think the universe is? As far as I know, but creationists and non-creationists agree the universe is very large and most galaxies are millions or billions of light years away. --[[User:BMcP|BMcP]] 08:29, 11 February 2010 (EST)

:BMcP, I explained this on your talk page many days ago, without a satisfactory response. We don't simply repeat, robot-like, the implausible or illogical claims of atheists here. You're in the wrong place for that. Mindless repetition of [[liberal]] claims may work on Wikipedia, but not here.

:An example is the claim that you've just reinserted that this galaxy will collide with Earth in many billions of years. It's a ludicrous, non-scientific assertion that is simply designed to pry people from the Bible and from God.

:I've begged you to reconsider the liberal assumptions with an open mind. I've begged you to open the Bible and spend some meaningful time reading it with an open mind. But I can't and wouldn't force you to do either. What I will do is keep the atheistic nonsense off this site, unless you want to post it under a new entry entitled "liberal claims lacking in scientific verification."

::The radial velocity of the Andromeda galaxy with respect to the Milky Way can be measured by examining the Doppler shift of spectral lines from stars in the galaxy. Using this the Andromeda Galaxy is approaching the Sun at about 100 to 140 kilometers per second.[http://www.space.com/scienceastronomy/astronomy/galaxy_collides_020507-1.html] We can then estimate how long it would be before the galaxies meet up using math. That is how we get the estimate of 2.5 billion or so years. I will however concede that the collision is uncertain because the two galaxies may move past each other instead because we cannot exactly measure Andromeda's transverse velocity. Because of that, I will change the text about the galaxies colliding to being uncertain. Is this acceptable?

Groombridge 34

2010-02-11T15:00:41Z

BMcP: Added Night Sky Template

{{Night Sky
| image =
| designation =GX/GQ Andromedae HD 1326
| rightascension =00h 18m 22.9s
| declination =+44o 01' 22"
| distance =11.62 ±0.04 ly
| constellation =[[Andromeda_(constellation)|Andromeda]]
| type =[[Binary star]]
| dimensions =
| magnitude =Absolute Mag: 10.33 Apparent Mag: 8.09(A)/11.06(B)
| redshift =
| radvelocity =+12.0 km/s
| propmotion =RA: 2888.92 mas/yr Dec.: 410.58 mas/yr
| parallax =280.59 ± 0.95 mas
}}
'''Groombridge 34''' is a binary star system located around 11.6 light years from our [[Sun]]. The system is located in the constellation [[Andromeda_(constellation)|Andromeda]], northwest of the [[Andromeda galaxy]]. Neither star is visible in the night sky to the unaided eye, with Groombridge 34 A having an apparent magnitude of 8.09 and Groombridge 34 B an apparent magnitude of only 11.06. Both stars of the Groombridge 34 AB system are [[flare star|flare stars]] and therefore also have the variable star designation of '''GX Andromedae''' and '''GQ Andromedae''' respectively.<ref>http://www.richweb.f9.co.uk/astro/nearby_stars.htm#WDS_GRB34</ref>

The binary star system was first mentioned in "A Catalog of Circumpolar Stars" by [[Stephen Groombridge]], published after his death in 1838. <ref>http://www.daviddarling.info/encyclopedia/G/Groombridge_34.html</ref> In 1860 it was discovered the system has a large proper motion relative to our own solar system.<ref>http://hyperphysics.phy-astr.gsu.edu/Hbase/Starlog/grm34.html</ref>

==Groombridge 34 A==

'''Groombridge 34 A''' is the more massive of the pair and is a main sequence [[red dwarf]] of the spectral class M1.5 Vne. The star has around 48.6 percent of the Sun's mass and 34 percent of its diameter.<ref name="recons>http://joy.chara.gsu.edu/RECONS/TOP100.posted.htm</ref> The star is very dim, with only 64/10,000th of the Sun's visual luminosity. <ref name="de">http://jumk.de/astronomie/near-stars/groombridge-34.shtml</ref> It is estimated that Groombridge 34 A is, on average, some 157 AU from its companion, with an orbital period of around 3,000 years.

==Groombridge 34 B==

'''Groombridge 34 B''' is cooler and dimmer then its companion with a spectral class of M3.5 Vne. It has some 16.3 percent of our Sun's mass and 19 percent of its diameter.<ref name="recons">http://joy.chara.gsu.edu/RECONS/TOP100.posted.htm</ref> The star is only some 42/10,000th as visually luminous as our Sun.<ref name="de">http://jumk.de/astronomie/near-stars/groombridge-34.shtml</ref>

Thus far no substellar companions have been located around either star of the Groombridge 34 system.<ref>http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2000AJ....119..906S&db_key=AST&high=38e0b7728703440</ref> For an [[Terrestrial planet|Earth-like]] world to be comfortable with liquid [[water]] on the surface, it would have to be around 0.25 AU from Groombridge 34 A and 0.13 from Groombridge 34 B when taking into account [[infrared]] [[radiation]]. However, if such a world exists, it would be very difficult for life to exist there as both stars in the Groombridge 34 system are [[flare star|flare stars]]. At the distance needed for liquid water to exist, the world would be exposed up to 10,000 times the normal [[X-ray]] output during a flare, which would be deadly to life as we know it.

[[Category:Astronomy]]
[[Category:Double Stars]]

==References==
{{reflist}}

Talk:Andromeda galaxy

2010-02-11T13:51:02Z

BMcP: /* Disclaimer */

Talk:Andromeda galaxy

2010-02-11T13:29:04Z

BMcP: /* Disclaimer */

Draco (constellation)

2010-02-11T13:17:56Z

BMcP: /* Stars and other features */ Why would distance be pulled out??

{{Constellation
| image =Draco constellation map.png
| rightascension =17h
| declination =+65o
| constellation =[[Boötes]] [[Hercules (constellation)|Hercules]] [[Lyra]] [[Cygnus (constellation)|Cygnus]] [[Cepheus (constellation)|Cepheus]] [[Ursa Minor]] [[Ursa Major]] [[Camelopardalis]]
| area =1083 sq. deg.
| starnumber =76 Bayer/Flamsteed stars
| mainstars =14
| brightstar =[[Gamma Draconis]] (Apparent Mag: 2.24)
| neareststar =Struve 2398 11.5 light years
| planets =5
| messier =1
| symbol =Dragon
}}
'''Draco''' is an extensive, circumpolar [[constellation]] located in the far northern [[celestial hemisphere]], almost encircling [[Ursa Minor]]. The constellation is most noted for the fact that [[Thuban]], the north star of the ancient world, is a member. Draco was one of the 48 constellations recorded by [[Ptolemy]] in his ''Almagest'' or Great Book, and is one of the 88 modern constellations.

==Mythological Background==

Likely recognized since the [[neolithic]] age, the constellation is among the earliest recorded in history. For the ancient [[Babylonians]], the constellation represented '''Tiamat''', whose body was split by [[Marduk]] to create the heavens and Earth. In [[ancient Egypt]], the constellation was known as '''Taweret''', the [[Egyptian]] goddess of childbirth, fertility, and of the northern skies. During this time, the star [[Thuban]] was the pole star, giving the appearance that the night sky revolved around the constellation. As such, one of the shafts from the burial chamber of the pharaoh [[Khufu]], inside the [[Great Pyramid]] pointed directly at the star.<ref>http://www.crystalinks.com/draco.html</ref>

In [[Greek mythology]], the constellation was associated with Draco, a [[dragon]] that lived in a far off land. According to the mythology, [[Cadmus]] traveled to this land with his soldiers as part his quest to find his sister, [[Princess_Europa|Europa]], who was previously kidnapped by [[Zeus]]. After being sent there by the [[Oracle]] of Delphi. The Dragon managed to kill all of Cadmus' soldiers while they searched for water before the [[Phoenicians|Phoenician]] prince slew it. The goddess [[Athena]] then appeared to him, and informed him to sow the teeth of the dragon into the ground. The teeth then became new soldiers that helped Cadmus found the city of [[Thebes]].<ref>http://seds.org/Maps/Stars_en/Fig/draco.html</ref>

In both Greek and [[Roman mythology]], Draco also represented the dragon called '''Ladon''', the legendary dragon that guarded the golden [[apple|apples]] in the garden of the [[Hesperides]]. [[Heracles]] was required to steal these apples as the eleventh of his twelve labors. He managed this feat by putting the dragon to sleep using music. Later, the goddess [[Hera]] placed the dragon into the sky and it became the constellation Draco.<ref name="starry">http://starryskies.com/The_sky/constellations/draco.html</ref>

In [[Chinese]] mythology, the constellation was seen as a dragon that consumed the [[Sun]] or [[Moon]] during an [[eclipse]]. The [[Persians]] saw Draco as a man-eating serpent known as '''Azhdeha'''. In early [[Hindu mythology]], Draco was seen as an [[alligator]] called '''Shi-shu-mara'''.<ref name="starry">http://starryskies.com/The_sky/constellations/draco.html</ref>

==Stars and other features==

In addition to the stars that make up the constellation, Draco has several other notable astronomical features. The [[Cat's Eye Nebula]] (NGC 6543), a [[planetary nebula]] some 3300 light years distant, is one of the deep sky objects located within the constellation. Others include the '''Draco Dwarf Galaxy''', a satellite of the [[Milky Way]], and the galaxy '''NGC 5866''', the latter located some 50 million light years away.

Despite [[Thuban]] having the alpha [[Bayer designation]], usually reserved for the brightest stars in a constellation, it is [[Eltanin]] (Gamma Draconis) that is the brightest star in Draco, with an apparent magnitude of 2.24.

===Named Stars===

*[[Thuban]] - Alpha Draconis (α Dra)
*Rastaban - Beta Draconis (β Dra)
*Eltanin - Gamma Draconis (γ Dra)
*Tyl - Epsilon Draconis (ε Dra)
*Al dhi'bah - Zeta Draconis (ζ Dra)
*Aldhibain - Eta Draconis (η Dra)
*Edasich - Iota Draconis (ι Dra)
*Gianfar - Lambda Draconis (λ Dra)
*Alrakis - Mu Draconis (μ Dra)
*Grumium - Xi Draconis (ξ Dra)
*Alsafi - Sigma Draconis (σ Dra)
*Dziban - Psi Draconis (ψ Dra)

[[Category:Astronomy]]

==References==
{{reflist}}

Gliese 581

2010-02-11T13:05:36Z

BMcP: /* Old Universe View */"Liberal" is an assumption, compromise has already been done for Old Universe view between editors, don't put in politics

{{Night Sky
| image =Gliese 581.jpg
| designation =HO Librae HIP 74995
| rightascension =15h 19m 26.8250s
| declination =−07o 43′ 20.209″
| distance =20.3 ±0.3 ly
| constellation =[[Libra]]
| type =[[Red dwarf]] [[Star]]
| dimensions =
| magnitude =Apparent Mag: 10,56 Absolute Mag: 11.6
| redshift =
| radvelocity =–−9.5 ±0.5 km/s
| propmotion =RA: −1233.51 mas/yr Dec.: −94.52 mas/yr
| parallax =160.91 ± 2.62 mas
}}
'''Gliese 581''', also known as '''HO Librae''', is a red dwarf star around 20.4 [[light year|light years]] away. It is most famous for the discovery of the [[Gliese 581c|first low mass planet within a star's habitable zone]]. In total, four planets have found thus far orbiting the star, two of which may sit within the [[habitable zone]].

Despite being only 20 light years distant Gliese 581 is invisible to the unaided eye. This is due to Gliese 581 being a [[red dwarf]], and thus dim, with an apparent magnitude of only 10.56.

==The Star==

Gliese 581 is a cool, dim, [[red dwarf]] in the main sequence with the spectral classification of M3 V. The star is one-third as massive as our own [[Sun]], with around 38 percent of its diameter. The star is only one percent as luminous as our Sun. However, much of the light emanating from Gliese 581 is in the infrared, therefore visually it is only 0.2 percent as bright. The star’s [[metallicity]] appears to be between 38 and 62 percent as enriched as our [[Sun]], according to its abundance of [[iron]].

==Planetary System==

There are four known planets in orbit around Gliese 581, with two inside the star’s [[habitable zone]]. The first, [[Gliese 581c|Gliese 581 c]], is the most widely reported. However '''Gliese 581 d''', discovered later, is a much better candidate for a [[Terrestrial Planet|terrestrial]], possibly life supporting world under current terrestrial [[climate]] models.

=== Gliese 581 b===

'''Gliese 581 b''' is the first planet discovered and the second closest known to its parent star. The planet was first discovered by a team of [[French]] and [[Swiss]] astronomers using the HARPS spectrograph and was announced on November 30, 2005. At the time, it was one of the smallest extrasolar worlds found and the fifth such potential terrestrial world to be found around a red dwarf star.<ref>http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2005A%26A...443L..15B&db_key=AST&data_type=HTML&format=&high=438efdb55325468</ref>

The planet has a minimum estimated mass of 15.65 times that of Earth. It orbits Gliese 581 in what is commonly called a "torch orbit", being only 0.04 AU (6 million kilometers) away, the orbit is so close that it only takes a little more than 5 days to complete.<ref name="exo">http://exoplanet.eu/star.php?st=Gl+581</ref>

===[[Gliese 581c|Gliese 581 c]]===

On April 25, 2007 the same team of astronomers, again using the HARPS spectrograp, announced the discovery of '''Gliese 581 c''' (along with Gliese 581 d). When announced, Gliese 581 c was the smallest known extrasolar planet around a main sequence [[star]] (until Gliese 581 e was found). It is the third closest of the four known worlds.

The planet is calculated to have at least 5.36 times [[Earth|Earth’s]] mass (maximum of 10.4 times), and is estimated to be 1.5 times the [[Earth|Earth’s]] diameter. The planet orbits with a mean distance of only 0.07 AU, which takes just under 13 days to complete. At this distance, Gliese 581 c is [[tidal lock|tidally locked]] to its parent star.<ref name="exo">http://exoplanet.eu/star.php?st=Gl+581</ref>

Initially the planet was thought to be inside Gliese 581’s [[habitable zone]], making it the first such terrestrial world outside of our Solar System to be found. This generate speculation about the possibility of the planet being suitable for life as we know it. However, further research indicated that the planet may be too close to the [[star]], thus causing a [[Venus]]-like runaway greenhouse effect in its [[atmosphere]] that would boil off any [[water]].<ref name="habit">http://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdf</ref> Gliese 581 d instead is the better candidate for habitability.

===Gliese 581 d===

'''Gliese 581 d''' was discovered alongside and announced at the same time as [[Gliese 581c|Gliese 581 c]], also sitting within the [[habitable zone]] of Gliese 581, and is now the prime candidate for habitability among the known worlds of the Gliese 581 system. It is the fourth of the four known worlds in distance from its parent star.

The planet has a mass between 7.09 and 13.8 times that of Earth. Gliese 581 d has a mean orbit of 0.22 AU, which it completes in 66.8 days.<ref name="exo">http://exoplanet.eu/star.php?st=Gl+581</ref> In April of 2009, after further studies, the planet was confirmed to be within the habitable zone where liquid water could exist with a greenhouse effect under the right atmospheric conditions.<ref name="habit">http://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdf</ref> The planet is thought to be too massive to be made only of rock and may have been an ice world at one time, with the abundant ices melting into deep worldwide [[ocean|oceans]] as the planet migrated closer to Gliese 581.<ref>http://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.html</ref>

=== Gliese 581 e===

The discovery of '''Gliese 581 e''' was announced on April 21, 2009. The planet is estimated to have a minimum mass only 1.9 times that of Earth making it the smallest [[extrasolar planet]] in the system and the smallest extrasolar planet known overall. Of the four known worlds it is nearest to its parent star.

The planet has a mean orbit of only 0.03 AU, which it completes in a mere 3 days. Because of its short distance, the planet is too close to be within Gliese 581’s habitable zone.<ref name="exo">http://exoplanet.eu/star.php?st=Gl+581</ref> It is unlikely to have an atmosphere because of the high temperatures and strong [[radiation]] it would receive at such a close distance to even a low mass [[star]].

==Old Universe View==
In the cosmological model of a billions of years old universe, astronomers have calculated the star to be between 2 and 4.3 billion years old,<ref name="exo">http://exoplanet.eu/star.php?st=Gl+581</ref> using measurements of Gliese 581’s kinematic characteristics and magnetic activity. More recent measurements of the star shows its brightness only varies slightly over time, suggesting it is even older.<ref>http://www.astronomy.com/asy/default.aspx?c=a&id=5619</ref>

[[Category:Astronomy]]

==References==
{{reflist}}

==Links==
*[http://exoplanet.eu/ Extrasolar Planets Encyclopaedia]
*[http://exoplanets.org/ ExoPlanets]

Gliese 581

2010-02-10T20:51:18Z

BMcP: /* Old Universe View */

{{Night Sky
| image =Gliese 581.jpg
| designation =HO Librae HIP 74995
| rightascension =15h 19m 26.8250s
| declination =−07o 43′ 20.209″
| distance =20.3 ±0.3 ly
| constellation =[[Libra]]
| type =[[Red dwarf]] [[Star]]
| dimensions =
| magnitude =Apparent Mag: 10,56 Absolute Mag: 11.6
| redshift =
| radvelocity =–−9.5 ±0.5 km/s
| propmotion =RA: −1233.51 mas/yr Dec.: −94.52 mas/yr
| parallax =160.91 ± 2.62 mas
}}
'''Gliese 581''', also known as '''HO Librae''', is a red dwarf star around 20.4 [[light year|light years]] away. It is most famous for the discovery of the [[Gliese 581c|first low mass planet within a star's habitable zone]]. In total, four planets have found thus far orbiting the star, two of which may sit within the [[habitable zone]].

Despite being only 20 light years distant Gliese 581 is invisible to the unaided eye. This is due to Gliese 581 being a [[red dwarf]], and thus dim, with an apparent magnitude of only 10.56.

==The Star==

Gliese 581 is a cool, dim, [[red dwarf]] in the main sequence with the spectral classification of M3 V. The star is one-third as massive as our own [[Sun]], with around 38 percent of its diameter. The star is only one percent as luminous as our Sun. However, much of the light emanating from Gliese 581 is in the infrared, therefore visually it is only 0.2 percent as bright. The star’s [[metallicity]] appears to be between 38 and 62 percent as enriched as our [[Sun]], according to its abundance of [[iron]].

==Planetary System==

There are four known planets in orbit around Gliese 581, with two inside the star’s [[habitable zone]]. The first, [[Gliese 581c|Gliese 581 c]], is the most widely reported. However '''Gliese 581 d''', discovered later, is a much better candidate for a [[Terrestrial Planet|terrestrial]], possibly life supporting world under current terrestrial [[climate]] models.

=== Gliese 581 b===

'''Gliese 581 b''' is the first planet discovered and the second closest known to its parent star. The planet was first discovered by a team of [[French]] and [[Swiss]] astronomers using the HARPS spectrograph and was announced on November 30, 2005. At the time, it was one of the smallest extrasolar worlds found and the fifth such potential terrestrial world to be found around a red dwarf star.<ref>http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2005A%26A...443L..15B&db_key=AST&data_type=HTML&format=&high=438efdb55325468</ref>

The planet has a minimum estimated mass of 15.65 times that of Earth. It orbits Gliese 581 in what is commonly called a "torch orbit", being only 0.04 AU (6 million kilometers) away, the orbit is so close that it only takes a little more than 5 days to complete.<ref name="exo">http://exoplanet.eu/star.php?st=Gl+581</ref>

===[[Gliese 581c|Gliese 581 c]]===

On April 25, 2007 the same team of astronomers, again using the HARPS spectrograp, announced the discovery of '''Gliese 581 c''' (along with Gliese 581 d). When announced, Gliese 581 c was the smallest known extrasolar planet around a main sequence [[star]] (until Gliese 581 e was found). It is the third closest of the four known worlds.

The planet is calculated to have at least 5.36 times [[Earth|Earth’s]] mass (maximum of 10.4 times), and is estimated to be 1.5 times the [[Earth|Earth’s]] diameter. The planet orbits with a mean distance of only 0.07 AU, which takes just under 13 days to complete. At this distance, Gliese 581 c is [[tidal lock|tidally locked]] to its parent star.<ref name="exo">http://exoplanet.eu/star.php?st=Gl+581</ref>

Initially the planet was thought to be inside Gliese 581’s [[habitable zone]], making it the first such terrestrial world outside of our Solar System to be found. This generate speculation about the possibility of the planet being suitable for life as we know it. However, further research indicated that the planet may be too close to the [[star]], thus causing a [[Venus]]-like runaway greenhouse effect in its [[atmosphere]] that would boil off any [[water]].<ref name="habit">http://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdf</ref> Gliese 581 d instead is the better candidate for habitability.

===Gliese 581 d===

'''Gliese 581 d''' was discovered alongside and announced at the same time as [[Gliese 581c|Gliese 581 c]], also sitting within the [[habitable zone]] of Gliese 581, and is now the prime candidate for habitability among the known worlds of the Gliese 581 system. It is the fourth of the four known worlds in distance from its parent star.

The planet has a mass of at least 7.09 (maximum of 13.8) times that of Earth. Glises 581 d has a mean orbit of 0.22 AU, which it completes in 66.8 days.<ref name="exo">http://exoplanet.eu/star.php?st=Gl+581</ref> In April of 2009, after further studies, the planet was confirmed to be within the habitable zone where liquid water could exist with a greenhouse effect under the right atmospheric conditions.<ref name="habit">http://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdf</ref> The planet is thought to be too massive to be made only of rock and may have been an ice world at one time, with the abundant ices melting into deep worldwide [[ocean|oceans]] as the planet migrated closer to Gliese 581.<ref>http://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.html</ref>

=== Gliese 581 e===

The discovery of '''Gliese 581 e''' was announced on April 21, 2009. The planet is estimated to have a minimum mass only 1.9 times that of Earth making it the smallest [[extrasolar planet]] in the system and the smallest extrasolar planet known overall. It is the closest of the four known worlds in distance from its parent star.

The planet has a mean orbit of only 0.03 AU, which it completes in a mere 3 days. Because of its short distance, the planet is too close to be within Gliese 581’s habitable zone.<ref name="exo">http://exoplanet.eu/star.php?st=Gl+581</ref> It is unlikely to have an atmosphere because of the high temperatures and strong [[radiation]] it would receive at such a close distance to even a low mass [[star]].

==Old Universe View==
In the cosmological model of a billions of years old universe, astronomers have calculated the star to be between 2 and 4.3 billion years old,<ref name="exo">http://exoplanet.eu/star.php?st=Gl+581</ref> using measurements of Gliese 581’s kinematic characteristics and magnetic activity. More recent measurements of the star shows its brightness only varies slightly over time, suggesting it is even older.<ref>http://www.astronomy.com/asy/default.aspx?c=a&id=5619</ref>

[[Category:Astronomy]]

==References==
{{reflist}}

==Links==
*[http://exoplanet.eu/ Extrasolar Planets Encyclopaedia]
*[http://exoplanets.org/ ExoPlanets]

Red dwarf

2010-02-10T20:50:27Z

BMcP: "Really long" doesn't work without frame of reference. Added in the Big Bang cosmology note, hopefully this is more acceptable.

[[Image:RedDwarfNASA.jpg|thumb|right|200px|Artist rendition of a red dwarf star.]]
A '''red dwarf''' is a relatively cool and dim main sequence [[star]] of either spectral class M or late K. Red dwarfs characteristically are the lowest mass stars in the main sequence, having less then one half of the mass of the [[Sun]], and may have as little as 0.075 times as much (any less and they would not be able to fuse hydrogen and instead becoming [[brown dwarf|brown dwarfs]]).<ref>http://spiff.rit.edu/classes/phys230/lectures/planneb/planneb.html</ref> Their surface temperatures averaging only around 2500 to 3500K. Red dwarfs are actually the most numerous class of stars in the [[galaxy]], making up more than half of all the stars including 21 of the 30 closest stars to our own [[Solar System]].<ref>http://www.daviddarling.info/encyclopedia/S/starsnearest.html</ref>

Red dwarfs, unlike higher mass stars, generate most of their surface energy entirely through [[convection]], instead of [[radiation]]. This is due the density of the star in relation to temperature, making it difficult for energy to be transported to the surface through the radiation process from the core. Because of this, red dwarfs can burn a proportionally higher percentage of their [[hydrogen]] fuel before evolving off of the main sequence, allowing these stars to have a lifespan that is longer then the 13.7 billion year estimated age of the [[universe]]<ref>Age according to Big Bang cosmology models</ref>. The lower a red dwarf's mass is, the longer the star will remain on the main sequence, with the lowest mass dwarfs having an estimated lifespan exceeding 10 trillion years.<ref>http://arxiv.org/abs/astro-ph/9701131v1</ref>

Despite being the most numerous type of stars in the galaxy, no red dwarf is visible in the night sky by the unaided eye even under the best conditions, including the closet star to us, [[Proxima Centauri]]. Even the largest red dwarf has a visual luminosity 10% of the Sun's, most have much less, with some as little as 1/10,000th the brightness.

===Planets around Red Dwarfs===
[[File:Gliese 581.jpg|thumb|right|200px|Artist rendition of Gliese 581 and its planetary system.]]
As the most common type of star in the galaxy, astronomers long wondered if planets orbited any red dwarfs. Since then several worlds have been found orbiting these stars including the small exoplanet orbiting the red dwarf star '''OGLE-2005-BLG-390L''' with a mass of only 5.5 times that of the Earth.<ref>http://www.nature.com/nature/journal/v439/n7075/full/nature04441.html</ref> This was the smallest known exoplanet until the discovery of a planet in orbit of [[Gliese 581]] in 2009 called [[Gliese_581#Gliese_581_e|Gliese 581 e]], which has a mass only 1.9 times the Earth.<ref>http://exoplanets.org/planets.shtml</ref> The red dwarf Gliese 581 also has a world, [[Gliese_581#Gliese_581_d|Gliese 581 d]], which is presently considered a decent candidate for habitability as it sits within the [[habitable zone]] of its parent star.<ref>http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?2007A%26A...476.1365V&db_key=AST&nosetcookie=1</ref>

It is debated if red dwarfs could have planets favorable to life as we understand it. This is due to the requirement that a [[habitable zone]] of red dwarf being extremely close to the star, due to the their low energy outputs. For planets close enough to be within a red dwarf's habitable zone, it would most likely be [[tidal lock|tidally locked]] to its parent star, allowing for potential extremes in temperature between the day and night sides. Red dwarfs also put out most of their energy in the form of [[infrared]] radiation, making [[photosynthesis]] very difficult, however this assumes a similar evolution of plant life. The greatest potential danger to possible life on such a close world is the fact many red dwarfs are [[flare star|flare stars]]. Flare stars occasionally increase their brightness for a few minute, but the real danger is the corresponding sudden increase of radiation across the [[electromagnetic spectrum]], including [[ultraviolet]] and [[x-ray]] radiation.

[[Category:Astronomy]]

==References==
{{reflist}}

Gliese 581

2010-02-10T19:58:26Z

BMcP: Added link

{{Night Sky
| image =Gliese 581.jpg
| designation =HO Librae HIP 74995
| rightascension =15h 19m 26.8250s
| declination =−07o 43′ 20.209″
| distance =20.3 ±0.3 ly
| constellation =[[Libra]]
| type =[[Red dwarf]] [[Star]]
| dimensions =
| magnitude =Apparent Mag: 10,56 Absolute Mag: 11.6
| redshift =
| radvelocity =–−9.5 ±0.5 km/s
| propmotion =RA: −1233.51 mas/yr Dec.: −94.52 mas/yr
| parallax =160.91 ± 2.62 mas
}}
'''Gliese 581''', also known as '''HO Librae''', is a red dwarf star around 20.4 [[light year|light years]] away. It is most famous for the discovery of the [[Gliese 581c|first low mass planet within a star's habitable zone]]. In total, four planets have found thus far orbiting the star, two of which may sit within the [[habitable zone]].

Despite being only 20 light years distant Gliese 581 is invisible to the unaided eye. This is due to Gliese 581 being a [[red dwarf]], and thus dim, with an apparent magnitude of only 10.56.

==The Star==

Gliese 581 is a cool, dim, [[red dwarf]] in the main sequence with the spectral classification of M3 V. The star is one-third as massive as our own [[Sun]], with around 38 percent of its diameter. The star is only one percent as luminous as our Sun. However, much of the light emanating from Gliese 581 is in the infrared, therefore visually it is only 0.2 percent as bright. The star’s [[metallicity]] appears to be between 38 and 62 percent as enriched as our [[Sun]], according to its abundance of [[iron]].

==Planetary System==

There are four known planets in orbit around Gliese 581, with two inside the star’s [[habitable zone]]. The first, [[Gliese 581c|Gliese 581 c]], is the most widely reported. However '''Gliese 581 d''', discovered later, is a much better candidate for a [[Terrestrial Planet|terrestrial]], possibly life supporting world under current terrestrial [[climate]] models.

=== Gliese 581 b===

'''Gliese 581 b''' is the first planet discovered and the second closest known to its parent star. The planet was first discovered by a team of [[French]] and [[Swiss]] astronomers using the HARPS spectrograph and was announced on November 30, 2005. At the time, it was one of the smallest extrasolar worlds found and the fifth such potential terrestrial world to be found around a red dwarf star.<ref>http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2005A%26A...443L..15B&db_key=AST&data_type=HTML&format=&high=438efdb55325468</ref>

The planet has a minimum estimated mass of 15.65 times that of Earth. It orbits Gliese 581 in what is commonly called a "torch orbit", being only 0.04 AU (6 million kilometers) away, the orbit is so close that it only takes a little more than 5 days to complete.<ref name="exo">http://exoplanet.eu/star.php?st=Gl+581</ref>

===[[Gliese 581c|Gliese 581 c]]===

On April 25, 2007 the same team of astronomers, again using the HARPS spectrograp, announced the discovery of '''Gliese 581 c''' (along with Gliese 581 d). When announced, Gliese 581 c was the smallest known extrasolar planet around a main sequence [[star]] (until Gliese 581 e was found). It is the third closest of the four known worlds.

The planet is calculated to have at least 5.36 times [[Earth|Earth’s]] mass (maximum of 10.4 times), and is estimated to be 1.5 times the [[Earth|Earth’s]] diameter. The planet orbits with a mean distance of only 0.07 AU, which takes just under 13 days to complete. At this distance, Gliese 581 c is [[tidal lock|tidally locked]] to its parent star.<ref name="exo">http://exoplanet.eu/star.php?st=Gl+581</ref>

Initially the planet was thought to be inside Gliese 581’s [[habitable zone]], making it the first such terrestrial world outside of our Solar System to be found. This generate speculation about the possibility of the planet being suitable for life as we know it. However, further research indicated that the planet may be too close to the [[star]], thus causing a [[Venus]]-like runaway greenhouse effect in its [[atmosphere]] that would boil off any [[water]].<ref name="habit">http://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdf</ref> Gliese 581 d instead is the better candidate for habitability.

===Gliese 581 d===

'''Gliese 581 d''' was discovered alongside and announced at the same time as [[Gliese 581c|Gliese 581 c]], also sitting within the [[habitable zone]] of Gliese 581, and is now the prime candidate for habitability among the known worlds of the Gliese 581 system. It is the fourth of the four known worlds in distance from its parent star.

The planet has a mass of at least 7.09 (maximum of 13.8) times that of Earth. Glises 581 d has a mean orbit of 0.22 AU, which it completes in 66.8 days.<ref name="exo">http://exoplanet.eu/star.php?st=Gl+581</ref> In April of 2009, after further studies, the planet was confirmed to be within the habitable zone where liquid water could exist with a greenhouse effect under the right atmospheric conditions.<ref name="habit">http://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdf</ref> The planet is thought to be too massive to be made only of rock and may have been an ice world at one time, with the abundant ices melting into deep worldwide [[ocean|oceans]] as the planet migrated closer to Gliese 581.<ref>http://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.html</ref>

=== Gliese 581 e===

The discovery of '''Gliese 581 e''' was announced on April 21, 2009. The planet is estimated to have a minimum mass only 1.9 times that of Earth making it the smallest [[extrasolar planet]] in the system and the smallest extrasolar planet known overall. It is the closest of the four known worlds in distance from its parent star.

The planet has a mean orbit of only 0.03 AU, which it completes in a mere 3 days. Because of its short distance, the planet is too close to be within Gliese 581’s habitable zone.<ref name="exo">http://exoplanet.eu/star.php?st=Gl+581</ref> It is unlikely to have an atmosphere because of the high temperatures and strong [[radiation]] it would receive at such a close distance to even a low mass [[star]].

==Old Universe View==
In the cosmological model of a billions of years old universe, astronomers have calculated to be between 2 and 4.3 billion years old,<ref name="exo">http://exoplanet.eu/star.php?st=Gl+581</ref> using measurements of Gliese 581’s kinematic characteristics and magnetic activity. More recent measurements of the star shows its brightness only varies slightly over time, suggesting it is even older.<ref>http://www.astronomy.com/asy/default.aspx?c=a&id=5619</ref>

[[Category:Astronomy]]

==References==
{{reflist}}

==Links==
*[http://exoplanet.eu/ Extrasolar Planets Encyclopaedia]
*[http://exoplanets.org/ ExoPlanets]

Gliese 581

2010-02-10T19:32:05Z

BMcP: Added Nightsky Template

{{Night Sky
| image =Gliese 581.jpg
| designation =HO Librae HIP 74995
| rightascension =15h 19m 26.8250s
| declination =−07o 43′ 20.209″
| distance =20.3 ±0.3 ly
| constellation =[[Libra]]
| type =[[Red dwarf]] [[Star]]
| dimensions =
| magnitude =Apparent Mag: 10,56 Absolute Mag: 11.6
| redshift =
| radvelocity =–−9.5 ±0.5 km/s
| propmotion =RA: −1233.51 mas/yr Dec.: −94.52 mas/yr
| parallax =160.91 ± 2.62 mas
}}

'''Gliese 581''', also known as '''HO Librae''', is a red dwarf star around 20.4 [[light year|light years]] away. It is most famous for the discovery of the [[Gliese 581c|first low mass planet within a star's habitable zone]]. In total, four planets have found thus far orbiting the star, two of which may sit within the [[habitable zone]].

Despite being only 20 light years distant Gliese 581 is invisible to the unaided eye. This is due to Gliese 581 being a red dwarf, and thus dim, with an apparent magnitude of only 10.56.

==The Star==

Gliese 581 is a cool, dim, [[red dwarf]] in the main sequence with the spectral classification of M3 V. The star is one-third as massive as our own [[Sun]], with around 38 percent of its diameter. The star is only one percent as luminous as our Sun. However, much of the light emanating from Gliese 581 is in the infrared, therefore visually it is only 0.2 percent as bright. The star’s [[metallicity]] appears to be between 38 and 62 percent as enriched as our [[Sun]], according to its abundance of [[iron]]. Using measurements of Gliese 581’s kinematic characteristics and magnetic activity, the star is calculated to be at least 2 billion years old, possibly as old as 4.3 billion years.<ref name="exo">http://exoplanet.eu/star.php?st=Gl+581</ref> More recent measurements of the star shows its brightness only varies slightly over time, suggesting it is even older.<ref>http://www.astronomy.com/asy/default.aspx?c=a&id=5619</ref>

==Planetary System==

There are four known planets in orbit around Gliese 581, with two inside the star’s [[habitable zone]]. The first, [[Gliese 581c|Gliese 581 c]], is the most widely reported. However '''Gliese 581 d''', discovered later, is a much better candidate for a [[Terrestrial Planet|terrestrial]], possibly life supporting world under current terrestrial [[climate]] models.

=== Gliese 581 b===

'''Gliese 581 b''' is the first planet discovered and the second closest known to its parent star. The planet was first discovered by a team of [[French]] and [[Swiss]] astronomers using the HARPS spectrograph and was announced on November 30, 2005. At the time, it was one of the smallest extrasolar worlds found and the fifth such potential terrestrial world to be found around a red dwarf star.<ref>http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2005A%26A...443L..15B&db_key=AST&data_type=HTML&format=&high=438efdb55325468</ref>

The planet has a minimum estimated mass of 15.65 times that of Earth. It orbits Gliese 581 in what is commonly called a "torch orbit", being only 0.04 AU (6 million kilometers) away, the orbit is so close that it only takes a little more than 5 days to complete.<ref name="exo">http://exoplanet.eu/star.php?st=Gl+581</ref>

===[[Gliese 581c|Gliese 581 c]]===

On April 25, 2007 the same team of astronomers, again using the HARPS spectrograp, announced the discovery of '''Gliese 581 c''' (along with Gliese 581 d). When announced, Gliese 581 c was the smallest known extrasolar planet around a main sequence [[star]] (until Gliese 581 e was found). It is the third closest of the four known worlds.

The planet is calculated to have at least 5.36 times [[Earth|Earth’s]] mass (maximum of 10.4 times), and is estimated to be 1.5 times the [[Earth|Earth’s]] diameter. The planet orbits with a mean distance of only 0.07 AU, which takes just under 13 days to complete. At this distance, Gliese 581 c is [[tidal lock|tidally locked]] to its parent star.<ref name="exo">http://exoplanet.eu/star.php?st=Gl+581</ref>

Initially the planet was thought to be inside Gliese 581’s [[habitable zone]], making it the first such terrestrial world outside of our Solar System to be found. This generate speculation about the possibility of the planet being suitable for life as we know it. However, further research indicated that the planet may be too close to the [[star]], thus causing a [[Venus]]-like runaway greenhouse effect in its [[atmosphere]] that would boil off any [[water]].<ref name="habit">http://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdf</ref> Gliese 581 d instead is the better candidate for habitability.

===Gliese 581 d===

'''Gliese 581 d''' was discovered alongside and announced at the same time as [[Gliese 581c|Gliese 581 c]], also sitting within the [[habitable zone]] of Gliese 581, and is now the prime candidate for habitability among the known worlds of the Gliese 581 system. It is the fourth of the four known worlds in distance from its parent star.

The planet has a mass of at least 7.09 (maximum of 13.8) times that of Earth. Glises 581 d has a mean orbit of 0.22 AU, which it completes in 66.8 days.<ref name="exo">http://exoplanet.eu/star.php?st=Gl+581</ref> In April of 2009, after further studies, the planet was confirmed to be within the habitable zone where liquid water could exist with a greenhouse effect under the right atmospheric conditions.<ref name="habit">http://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdf</ref> The planet is thought to be too massive to be made only of rock and may have been an ice world at one time, with the abundant ices melting into deep worldwide [[ocean|oceans]] as the planet migrated closer to Gliese 581.<ref>http://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.html</ref>

=== Gliese 581 e===

The discovery of '''Gliese 581 e''' was announced on April 21, 2009. The planet is estimated to have a minimum mass only 1.9 times that of Earth making it the smallest [[extrasolar planet]] in the system and the smallest extrasolar planet known overall. It is the closest of the four known worlds in distance from its parent star.

The planet has a mean orbit of only 0.03 AU, which it completes in a mere 3 days. Because of its short distance, the planet is too close to be within Gliese 581’s habitable zone.<ref name="exo">http://exoplanet.eu/star.php?st=Gl+581</ref> It is unlikely to have an atmosphere because of the high temperatures and strong [[radiation]] it would receive at such a close distance to even a low mass [[star]].

[[Category:Astronomy]]

==References==
{{reflist}}

==Links==
*[http://exoplanet.eu/ Extrasolar Planets Encyclopaedia]
*[http://exoplanets.org/ ExoPlanets]

Delta Pavonis

2010-02-10T17:41:40Z

BMcP: Added Nightsky Template

{{Night Sky
| image =
| designation =HD 190248 HIP 99240
| rightascension =20h 08m 43.6084s
| declination =−66o 10′ 55.446″
| distance =19.92 ±0.08 ly
| constellation =[[Pavo]]
| type =[[Star]]
| dimensions =
| magnitude =Apparent Mag: 3.56 Absolute Mag: 4.62
| redshift =
| radvelocity =–21.7 ±0.9 km/s
| propmotion =RA: 1210.50 ±0.58 mas/yr Dec.: −1130.27 ±0.44 mas/yr
| parallax =163.74 ±0.65 mas
}}

'''Delta Pavonis''' is a nearby star similar to our [[Sun]], although smaller and dimmer. It is located some 19.9 light years distant, in the constellation of [[Pavo]]. The star has an apparent magnitude of 3.56, allowing it to be visible to the unaided eye in dark skies.

Delta Pavonis is a yellow-orange [[star]] on the main sequence of spectral type G5-8 V-IV. The star is 1.06 times our Sun's diameter, and is 1.1 times as massive.<ref>http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1983ApJS...53..643J</ref> The star is also some 1.18 times as luminous. As Delta Pavonis is usually bright for its spectral type, it is suspected that the star is beginning to evolve off the main sequence on its way to becoming a subgiant star as it starts to fuse more and more helium at its core.<ref>G. F. Porto de Mello, E. F. del Peloso, L. Ghezzi (2006). "Astrobiologically interesting stars within 10 parsecs of the Sun". Astrobiology 6 (2): 308–331</ref>

Based on the abundance of [[iron]] measured for Delta Pavonis, the star is estimated to be 95 percent to 2.7 times [[Metallicity|as enriched as our Sun]] with elements heavier than [[hydrogen]].<ref>http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1992A%26AS...95..273C</ref>

Because Delta Pavonis is relatively close and is similar to our sun, it has garnered a high amount of interest as a system where [[Terrestrial Planet|Earth-like]] planets may exist. The orbital distance such a planet would need to have liquid water on its surface is around 1.09 AU, or a little farther than Earth is from our Sun. Astronomers for both NASA's [[Terrestrial Planet Finder]] and the ESA's Darwin are hoping to find worlds within Delta Pavonis' [[habitable zone]] once the missions are launched. SETI has also expressed interest in the star, calling it the "Best SETI target" in a survey of nearby stars.<ref>http://adsabs.harvard.edu/abs/2003ApJS..149..423T</ref> At present, there are no known sub-stellar companions orbiting Delta Pavonis.

[[Category:Astronomy]]

==References==
{{reflist}}

Castor

2010-02-10T16:40:07Z

BMcP: Added link

[[Image:Gemini constellation map.png|thumb|right|338px|Location of Castor in the constellation of Gemini]]
'''Castor''', also known as '''Alpha Geminorum''', is a star system in the constellation [[Gemini]]. Despite the star's alpha [[Bayer designation]], it is the second brightest star of the Gemini constellation, with a total apparent magnitude of 1.58.<ref name="illinois">http://stars.astro.illinois.edu/sow/castor.html</ref> Originally thought as a single binary star system, the Castor system is actually three sets of tight, [[Binary_stars#Spectroscopic_Binaries|spectroscopic binary stars]]. Based on measurements from the [[Hipparcos]] mission, it is estimated that the Castor system is 51.6 light years away.<ref name="illinois">http://stars.astro.illinois.edu/sow/castor.html</ref>

The modern name for the [[star]], Castor, is named for the character of the same name in [[Greek mythology]], who was one of the twin sons of [[Zeus]] and Leda. During the era of [[ancient Greece]] though, the star was called Ἀπόλλων, (pronounced apóllɔːn), meaning Apollo. In [[Arabic]], the star was called ''Al Rās al Taum al Muḳaḍḍim'', meaning the Head of the Foremost Twin.<ref>http://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Gemini*.html</ref>

==Star System==

The first binary pair, Castor A, has a class A dwarf as its primary star (Castor Aa). Astronomers haven't been able to determine decidedly if its secondary star (Castor Ab) is a class M red dwarf or a class A dwarf. Castor B, the second binary pair, is the same. These first two binary pairs orbit each other with an average separation of 104 AU, and take around 445 years to complete. The orbit though quite elliptical and the two pairs get as close as 71 AU, and as far apart as 138 AU.<ref name="illinois">http://stars.astro.illinois.edu/sow/castor.html</ref> The third binary pair (Castor C) is made up of two, faint class M dwarfs and is separated from the inner quadruple of stars by more than 1,100 AU, with an orbit that may take 10,000 years to complete. These two outer stars are both considered [[flare star|flare stars]] and thus also designated with the variable star name of '''YY Geminorum AB'''.

===Castor Aa===

The primary star of the Castor A binary pair, '''Castor Aa''', is a main sequence blue-white star of spectral class A1 V, similar to [[Sirius]]. The star is estimated to have a mass 2.15 times that of our [[Sun]], with a radius 2.3 times as great. The bright, blue-white star has a visual luminosity between 17 and 34 times that of our Sun. Both Castor Aa and its companion have a lower [[metallicity]] then our own Sun.<ref name="harv">http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2001A%26A...365L.344G&db_key=AST&high=3c1a46b25823484</ref> Castor Aa is separated from its companion Ab by an average distance of only 0.022 AUs, but their [[orbit]] is highly eccentric (e=0.499). It takes a total of 9.21 days for the two stars to complete an orbit.<ref name="harv1">http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1914ApJ....39..459S&data_type=PDF_HIGH&type=PRINTER&ext=.pdf</ref>

===Castor Ab===

'''Castor Ab''' is a main sequence dwarf star, however its spectral type is not exactly known. The star may be either a class M red dwarf or a class A blue-white dwarf, similar to Castor Aa.<ref name="harv2">http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1983ApJ...271..264G&data_type=PDF_HIGH&type=PRINTER&ext=.pdf</ref>. The star is estimated to have a mass that ranges from 40 to 60 percent greater then our own Sun. The star's radius and luminosity is not known. Castor Ab has been repeatedly observed having frequent broadband and [[x-ray]] flares, normally associated with red dwarf stars.<ref name="harv">http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2001A%26A...365L.344G&db_key=AST&high=3c1a46b25823484</ref>

The combined visual luminosity of Castor Aab is more than 34 times that of the Sun. For an [[terrestrial planet|Earth-like]] world to comfortably maintain liquid [[water]] on its surface, the hypothetical planet would have to orbit more than 6.0 AU from the Castor Aab pair, comparable to an orbit distance of [[Jupiter]] from our Sun.

===Castor Ba===

The primary star of the Castor B binary pair, '''Castor Ba''', is a blue-white, main sequence star of spectral class A2-5 Vm. The star is considered to be similar to [[Fomalhaut]]. Castor Ba is estimated to have a mass 1.7 times that of our [[Sun]], and some 1.6 times its diameter. The star has some 14 times the visual luminosity of our Sun.<ref name="harv">http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2001A%26A...365L.344G&db_key=AST&high=3c1a46b25823484</ref> The Castor B pair have a highly circular orbit around each other (e=0.01), with an average distance of 0.03 AUs, allowing them to complete an orbit in only 2.93 days.<ref name="harv1">http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1914ApJ....39..459S&data_type=PDF_HIGH&type=PRINTER&ext=.pdf</ref>

===Castor Bb===

Like Castor Ab, the second star of the Castor B binary is a main sequence dwarf of an unknown spectral type. The star may be a class M [[red dwarf]] or a class A blue-white dwarf, much like its primary companion. The question of the star's spectral type stems from the fact, like Castor Ab, there are frequent [[x-ray]] flares from the star. The mass of this star is also estimated to range from 40 to 60 percent more then our Sun, although its visual luminosity and diameter may be less than the Sun.<ref name="harv2">http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1983ApJ...271..264G&data_type=PDF_HIGH&type=PRINTER&ext=.pdf</ref>

For an [[terrestrial planet|Earth-like]] planet that orbits the Castor Bab pair, the distance the star needs to be for liquid [[water]] to comfortably exist on its surface, is around 4.0 AU - about the same distance of the [[Asteroid Belt]] from our [[Sun]].

===Castor Ca===

'''Castor Ca''', also know by its variable star name '''YY Geminorum Aa''', is a red, main sequence dwarf of spectral type M0.5 Ve. Like the other two binary pairs, it is part of a spectroscopic binary. Castor Ca is only 2.6 percent as visually luminous as our own Sun. The Star contains 62 percent of the Sun's mass by comparison and 76 percent of its diameter. Like many class M stars, Castor Ca is a variable [[flare star]] that frequently flares, especially in the x-ray range of the spectrum.<ref name="harv3">http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1994A%26A...287..843S&data_type=PDF_HIGH&type=PRINTER&ext=.pdf</ref>

Castor Ca and Cb are, on average, some 0.018 AUs apart in their circular orbit. This allows the two stars to complete an orbit in only 19.5 hours.<ref name="harv3">http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1994A%26A...287..843S&data_type=PDF_HIGH&type=PRINTER&ext=.pdf</ref> From our vantage poin on Earth, one star will regularly eclipse the other during their orbit, as the two star's orbit is very near the line of sight. Because of the very close orbit, both stars rotate rapidly from the resultant tidal forces.

===Castor Cb===

The companion Castor Cb, also called by its variable star name, '''YY Geminorum Ab''', is a main sequence red dwarf of spectral type M0.5 Ve. The star has 68 percent of the Sun's diameter and 57 percent of its mass. It is estimated to be only 2.6 as visually luminous as the Sun.<ref name="harv3">http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1994A%26A...287..843S&data_type=PDF_HIGH&type=PRINTER&ext=.pdf</ref>

For an [[terrestrial planet|Earth-like]] world to sustain liquid water on its surface comfortably, the hypothetical planet's orbit would be centered around 0.23 Au from the Castor Cab pair. This would be a closer orbit than that of [[Mercury]] around our Sun. At such a close orbit, the world would be [[tidal lock|tidally locked]] to the star pair and be highly vulnerable to the occasion massive flares.

[[Category:Astronomy]]
[[Category:Double Stars]]

==References==
{{reflist}}

Achernar (star)

2010-02-10T16:31:17Z

BMcP: /* Old Universe View */

{{Night Sky
| image =
| designation =Alpha Eridani HD 10144
| rightascension =01h 37m 42.85s
| declination =57o 14′ 12.3″
| distance =139 ±3 ly
| constellation =[[Eridanus]]
| type =[[Star]]
| dimensions =
| magnitude =Absolute Mag: -2.27 Apparent Mag: 0.50
| redshift =
| radvelocity =16 km/s
| propmotion =RA: 87.00 ±0.58 mas/yr Dec.: −38.24 ±0.50 mas/yr
| parallax =023.39 ±0.57 mas
}}
'''Achernar''', also known as '''Alpha Eridani''', is the brightest star of the constellation [[Eridanus]], and the ninth brightest star overall in the night sky. The [[star]] is not well known to those in the northern hemisphere, as it is only visible to those who live south of 32 degrees north latitude. South of 33 degrees south latitude, the star is [[circumpolar]].

The name Achernar, sometimes spelled as '''Achenar''', is derived from the Arabic آخر النهر ''ākhir an-nahr'', meaning "the End of the River". In Chinese though, the star is called 水委一 (''Shuǐwěiyī''), meaning "the First Star of the Crooked Running Water".<ref>Star-names and Their Meanings, Richard Hinckley Allen, New York: G. E. Stechert, 1899, p. 218</ref>

Achernar is a blue main sequence star of spectral type B3 Vpe, located 144 light years away. The star's mass is between six and eight times that of our [[Sun]],<ref name="harvard">http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1988BAICz..39..329H</ref> and 14.4 to 24 times its diameter.<ref>http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2003A%26A...407L..47D</ref> The star is 1,070 times as visually luminous as the Sun, but depending on the estimate of [[ultraviolet]] [[radiation]] the star emits, is 2,900 to 5,400 times as great as the Sun in total luminosity. Surface temperature estimates range from 14,500 to 19,300 K.
[[Image:Position Alpha Eri.png|thumb|left|154px|Location of Achernar in the constellation of Eridanus, as indicated by the pink arrow.]]
A fast-rotating star, Achernar has a spin velocity of 225 to 300 kilometers per second, completing a rotation of only 2.1 days, causing the star to eject mass at a rate thousands of times greater than our Sun. Because of this, Achernar is classified as a "Be" (B-emission) star, with an expanding circumstellar envelope of gas circulating around the [[equator]]. The tremendous speed also gives Achemar a distinct oblate spheroid shape. Its equatorial radius measures some 11.6 Suns across, while the polar radius measures only 7.5 Suns across, making the star more than 50 percent wider at the equator than at the poles.<ref name="harvard">http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1988BAICz..39..329H</ref>

There are no known substaller companions to Achernar. For an [[terrestrial planet|Earth-like]] to have liquid water on its surface, the hypothetical planet's orbit would be centered around 54 to 73 AUs, an orbit greater then the orbit of [[Pluto]]. At such a distance, the planet would take between 160 and 260 years to orbit Achernar.<ref>http://www.solstation.com/x-objects/achernar.htm</ref>

==Old Universe View==

In the cosmological model of a billions of years old universe, Achernar is theorized to be a couple hundred million years old, young enough to still be fusing [[hydrogen]] into [[helium]] in its core. Because of the star's high mass, it will burn through its core fuel quickly however, and eventually evolve into a large white dwarf, much like [[Sirius#Sirius_B|Sirius B]].<ref>http://stars.astro.illinois.edu/sow/achernar.html</ref>

[[Category:Astronomy]]

==References==
{{reflist}}

Achernar (star)

2010-02-10T16:30:33Z

BMcP: /* Old Universe View */

{{Night Sky
| image =
| designation =Alpha Eridani HD 10144
| rightascension =01h 37m 42.85s
| declination =57o 14′ 12.3″
| distance =139 ±3 ly
| constellation =[[Eridanus]]
| type =[[Star]]
| dimensions =
| magnitude =Absolute Mag: -2.27 Apparent Mag: 0.50
| redshift =
| radvelocity =16 km/s
| propmotion =RA: 87.00 ±0.58 mas/yr Dec.: −38.24 ±0.50 mas/yr
| parallax =023.39 ±0.57 mas
}}
'''Achernar''', also known as '''Alpha Eridani''', is the brightest star of the constellation [[Eridanus]], and the ninth brightest star overall in the night sky. The [[star]] is not well known to those in the northern hemisphere, as it is only visible to those who live south of 32 degrees north latitude. South of 33 degrees south latitude, the star is [[circumpolar]].

The name Achernar, sometimes spelled as '''Achenar''', is derived from the Arabic آخر النهر ''ākhir an-nahr'', meaning "the End of the River". In Chinese though, the star is called 水委一 (''Shuǐwěiyī''), meaning "the First Star of the Crooked Running Water".<ref>Star-names and Their Meanings, Richard Hinckley Allen, New York: G. E. Stechert, 1899, p. 218</ref>

Achernar is a blue main sequence star of spectral type B3 Vpe, located 144 light years away. The star's mass is between six and eight times that of our [[Sun]],<ref name="harvard">http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1988BAICz..39..329H</ref> and 14.4 to 24 times its diameter.<ref>http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2003A%26A...407L..47D</ref> The star is 1,070 times as visually luminous as the Sun, but depending on the estimate of [[ultraviolet]] [[radiation]] the star emits, is 2,900 to 5,400 times as great as the Sun in total luminosity. Surface temperature estimates range from 14,500 to 19,300 K.
[[Image:Position Alpha Eri.png|thumb|left|154px|Location of Achernar in the constellation of Eridanus, as indicated by the pink arrow.]]
A fast-rotating star, Achernar has a spin velocity of 225 to 300 kilometers per second, completing a rotation of only 2.1 days, causing the star to eject mass at a rate thousands of times greater than our Sun. Because of this, Achernar is classified as a "Be" (B-emission) star, with an expanding circumstellar envelope of gas circulating around the [[equator]]. The tremendous speed also gives Achemar a distinct oblate spheroid shape. Its equatorial radius measures some 11.6 Suns across, while the polar radius measures only 7.5 Suns across, making the star more than 50 percent wider at the equator than at the poles.<ref name="harvard">http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1988BAICz..39..329H</ref>

There are no known substaller companions to Achernar. For an [[terrestrial planet|Earth-like]] to have liquid water on its surface, the hypothetical planet's orbit would be centered around 54 to 73 AUs, an orbit greater then the orbit of [[Pluto]]. At such a distance, the planet would take between 160 and 260 years to orbit Achernar.<ref>http://www.solstation.com/x-objects/achernar.htm</ref>

==Old Universe View==

In the cosmological model of a billions of years old universe Achernar is theorized to be a couple hundred million years old, young enough to still be fusing [[hydrogen]] into [[helium]] in its core. Because of the star's high mass, it will burn through its core fuel quickly however, and eventually evolve into a large white dwarf, much like [[Sirius#Sirius_B|Sirius B]].<ref>http://stars.astro.illinois.edu/sow/achernar.html</ref>

[[Category:Astronomy]]

==References==
{{reflist}}

Canopus

2010-02-10T16:17:05Z

BMcP: Added Nightsky Template

{{Night Sky
| image =Canopus.jpg
| designation =Alpha Carinae
| rightascension =06h 23m 57.1099s
| declination =-52o 41′ 44.378″
| distance =310 ±20 ly
| constellation =[[Carina]]
| type =[[Supergiant]] [[Star]]
| dimensions =
| magnitude =Absolute Mag: -0.72 Apparent Mag: -5.53
| redshift =
| radvelocity =20.5 km/s
| propmotion =RA: 19.99 mas/yr Dec.: 23.67 mas/yr
| parallax =10.43 ±0.53 mas
}}

'''Canopus''', also known as '''Alpha Carinae''', is the brightest star in the constellation of [[Carina]]. It is also the second brightest star in the night sky, with only [[Sirius]] appearing more luminous. The [[star]] has an apparent magnitude of -0.72, making it easily visible in even heavily light polluted skies.

Because Canopus is 53 degrees south of the [[celestial equator]], it is not visible in latitudes above 37 degrees north, which includes most of [[Europe]], all of [[Canada]], and half the continental [[United States]]. The star itself is a rare example of a F class [[supergiant]].<ref name="simbad">http://simbad.u-strasbg.fr/simbad/sim-id?Ident=name+canopus</ref>

==Canopus in History==

Because of its brightness, Canopus has been known since [[antiquity]] and is important to [[navigation]]. Before the invention of the magnetic [[compass]], the star served as a southern pole star for navigators in the northern hemisphere far south enough to view the star. The [[Bedouin]] of the desert regions around the [[Levant]] used the star as one of the two main stars for navigation at night, the other being [[Polaris]].<ref>http://www.jstor.org/pss/613801</ref> Today Canopus is popular for space navigation, thanks to its brightness and distance from the ecliptic. Several spacecraft use a camera called the "Canopus Star Tracker" to help determine attitude.

The name Canopus itself is a [[Latin]] derivative of the [[Greek]] name ''Kanôbos'', first recorded in [[Ptolemy|Ptolemy's]] famous [[Almagest]], or "Great Book".<ref name="allen">Allen, Richard Hinckley (1963). Star Names: Their Lore and Meaning (Revised ed.). New York: Dover Publications. pp. 67–72. ISBN 0486210790.</ref> The exact origin of the name though is lost in time, although there are a couple hypotheses to its origin:
:*Canopus was once the brightest star of the ancient constellation of Argo, the ship Jason and the Argonauts used to search for the Golden Fleece in [[Greek mythology]]. The star itself was named after another ship's pilot.
:*From the [[Egyptian]] [[Copic]] name ''Kahi Nub'', meaning "Golden Earth", possibly because the star appeared more yellowish, thanks to the reddening effect by the [[atmosphere]] on the star's light at its position near the horizon.<ref name="allen">Allen, Richard Hinckley (1963). Star Names: Their Lore and Meaning (Revised ed.). New York: Dover Publications. pp. 67–72. ISBN 0486210790.</ref>

Other names for the star include '''Suhali''', occasionally used in English, based off of the Arabic name for various bright stars , سهيل ''suhayl''. The [[Chinese]] referred to the star as 老人星 or ''Lǎorénxīng'', meaning "Star of the Old". In Ancient [[India]], it was known as '''Agasti''' or '''Agastya'''. <ref name="allen">Allen, Richard Hinckley (1963). Star Names: Their Lore and Meaning (Revised ed.). New York: Dover Publications. pp. 67–72. ISBN 0486210790.</ref>

==Ths Star==

The true distance of the star was not known until the 1990s, and estimates beforehand varied from 96 light years away to some 1200 light years. The [[Hipparcos]] satellite telescope finally established the distance of the star to be around 310 light years away.<ref name="simbad">http://simbad.u-strasbg.fr/simbad/sim-id?Ident=name+canopus</ref>

Canopus itself is a rare spectral class F0 Ia yellow-white [[supergiant]]. The star may be either evolving towards or away from red supergiant status, but such stars as Canopus are still poorly understood. The star itself is 13,300 times as bright as our [[Sun]]. It is some 71 times the Sun's diameter and some 8 to 9 times our Sun's mass. If it was in the center of our solar system it would extend to within 90 percent of Mercury's orbit. The surface temperature of Canopus is estimated to be 7280 K, typical for a star in the F class. The [[corona]] of Canopus however is some ten times as hot as our Sun's corona, and is a considerable source of [[x-ray|X-rays]].<ref name="illinois">http://stars.astro.illinois.edu/sow/canopus.html</ref>

There are no known substellar companions of Canopus. For an [[terrestrial planet|Earth-like]] world to exist comfortably with liquid water on its surface around Canopus, it would have to be around three times the distance [[Pluto]] is from the Sun.

Canopus is in the [[helium]] burning phase of its evolution. Depending on its true mass, the star may eventually [[supernova]] or it will cease fusing elements at its core before the required fusion into [[iron]] needed to cause a supernovae collapse. If the latter is true, the star may end its life as a rare [[neon]]-[[oxygen]] [[white dwarf]] (most white dwarfs are mainly made up of carbon and oxygen).<ref name="illinois">http://stars.astro.illinois.edu/sow/canopus.html</ref>

[[Category:Astronomy]]

==References==
{{reflist}}

Arcturus

2010-02-10T15:50:31Z

BMcP: Added Nightsky Template

{{Night Sky
| image =000Bootes constellation map.jpg
| designation =Alpha Boötis
| rightascension =14h 15m 39.7s
| declination =+19o 10' 56"
| distance =36.7 ±0.3 ly
| constellation =[[Boötes]]
| type =[[Star]]
| dimensions =
| magnitude =Absolute Mag: -0.29 Apparent Mag: -0.04
| redshift =
| radvelocity =+5 km/s
| propmotion =RA: −1093.45 mas/yr Dec.: −1999.40 mas/yr
| parallax =88.98 ±0.68 mas
}}

'''Arcturus''', also known as '''Alpha Boötis''', is a star located some 36.7 light years from our [[Sun]]. It is the brightest star in the constellation [[Boötes]]. Arcturus is the fourth brightest star overall in the night sky after [[Sirius]], [[Canopus]], and [[Alpha Centauri|Alpha Centauri AB]] (the two stars are too close to resolve separately with the unaided eye), and the brightest one located in the northern celestial hemisphere, with an apparent magnitude of -0.05.<ref>http://www.atlasoftheuniverse.com/stars.html</ref> Arcturus is a single star, although in the 1990's it was thought to possibly have a stellar companion.<ref>http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1999PASP..111..556T&db_key=AST&high=3bd70156a918794</ref>

Arcturus has the second largest proper motion of first magnitude stars (only [[Alpha Centauri|Alpha Centauri's]] is greater), as observed from [[Earth]]. This motion was first detected by Edmond Halley in 1718. Right now, Arcturus is at its closest proximity to our [[solar system]], having become visible around a half million years ago, and will fade from view in another half million years as it moves away.

==Arcturus in History==

Arcturus is well known worldwide since [[antiquity]], thanks to the fact that it is one of the brightest stars in the night sky.

The star was known by ancient [[Polynesian]] navigators as '''Hōkūleʻa''', the "Star of Joy". The Polynesians knew the star was at its zenith over the [[Hawaii|Hawaiian islands]] and used this knowledge to sail from [[Tahiti]] and the Marquesas Islands to Hawaii. For their return trip, the Polynesians would use [[Sirius]], the zenith star of Tahiti. This trip has been duplicated several times using the same wayfinding technique of navigation through the use of these same stars since 1976 by the Polynesian Voyaging Society.

The star was known as ''Marpean-kurrk'' to the Koori of [[Australia]], its appearance signifying the birth of the larvae of the wood-ant in spring. The start of summer would be signaled by the star setting with the Sun. It was also seen as the mother of Antares (known to them as ''Djuit'').<ref>Mudrooroo (1994). Aboriginal mythology : an A-Z spanning the history of aboriginal mythology from the earliest legends to the present day. London: HarperCollins. p. 5. ISBN 1855383063.</ref>

The name Arcturus is a derivative of the [[Ancient Greek]] Αρκτοῦρος, meaning "Guardian of the Bear". This was in reference to the constellation [[Boötes]], which is next to [[Ursa Major]] and [[Ursa Minor]], the Greater and Lesser Bears. According to [[Greek mythology]], the star was created by [[Zeus]] for the purpose of guarding these constellations, referred to as Callisto and her son Arcas.

The star is also mentioned in the [[Old Testament]] of the ''Bible'' in the [[King James Version]]:

{{Bible quote|Which maketh Arcturus, Orion, and Pleiades, and the chambers of the south.|book=Job|chap=9|verses=9|version=KJV}}

{{Bible quote|Canst thou bring forth Mazzaroth in his season? or canst thou guide Arcturus with his sons?|book=Job|chap=38|verses=32|version=KJV}}

In the actual [[Hebrew]], it is translated as עיש, or ''Ayish'', and it is typically associated with Ursa Major, although the exact meaning is disputed and controversial owing to the general obscurity of ancient terminology.<ref>http://www.jewishencyclopedia.com/view.jsp?artid=749&letter=C</ref>

In [[Arabic]] the star's full name is referred to as السماك الرامح ''as-simāk ar-rāmiħ'', or "the uplifted one of the lancer". It is one of two stars called ''al-simāk'', or "the uplifted one", the other being Spica.<ref>Richard Hinckley Allen, Star-names and their meanings (1936), p. 100-101.</ref> This shortened name has been romanized in [[Medieval]] [[Europe]] to such names as '''Aramec''', '''Azimech''', and '''Alramih'''. Another Arabic term for the star is حارس السماء ''ħāris al-samā’'' or "the keeper of heaven".<ref>Hans Wehr (J.M. Cowan ed.), A dictionary of modern written Arabic (1994).</ref>

For the [[Chinese]], the star is located in the constellation known as 角宿, ''Jiao Xiu'', of which it is the brighest star. Because of this, the star is called 大角, ''Da Jiao'', or "Great Horn". It is also part of the constellation of 亢宿, ''Kang Xiu''.

During the 1933 World Fair in [[Chicago]], the light from Arcturus was collected and used to start a series of switches to illuminate and officially open the fair. This was based on the conclusion at the time that Arcturus was 40 light years distant, therefore light originating from the star during the 1896 World Fair in Chicago, 40 years prior, would have reached here for the 1933 fair.<ref>http://www.space.com/scienceastronomy/brightest_stars_030715-4.html</ref>

==The Star==
[[Image:000Arcturus-star.jpg|thumb|right|200px|Comparison in size between Arcturus and the [[Sun]]. Copyright © Windows to the Universe [http://www.windows.ucar.edu/]. Used with permission.]]
Arcturus is an orange-red giant of the spectral type K1.5 IIIpe. The star has some 24.5 times the diameter of our [[Sun]]. Like all giants, it has a low mass compared to its size, having only 1.5 times the mass of our Sun.<ref name="illinois">http://www.astro.illinois.edu/~jkaler/sow/arcturus.html</ref> Arcturus is 115 times as bright as our sun visually, although its absolute magnitude is 215 times as great counting the [[infrared]].<ref>http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2002hgs..book.....K&db_key=AST&data_type=HTML&format=&high=45e3861c6616357</ref> The star has rather low [[metallicity]], being only 17 to 32 percent as abundant as our Sun in elements heavier then [[hydrogen]], based on its abundance of [[iron]].<ref>http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1998Obs...118..299G&data_type=PDF_HIGH&type=PRINTER</ref>

Arcturus is an older star, even possibly a [[metallicity|Population II]] star, forming in the thick disk that lies thousands of light years above and below the galactic plane. As Arcturus is more massive then our sun, it burned through its core fuel of [[hydrogen]] faster, likely exhausting it in five to eight billion years and evolving into a giant.<ref name="illinois">http://www.astro.illinois.edu/~jkaler/sow/arcturus.html</ref> Arcturus may have only recently entered this stage, its mass indicating the star hasn't yet suffered from substantial loss of material after leaving the main sequence.<ref>http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1977ApJ...214..410A&data_type=PDF_HIGH&type=PRINTER</ref>

As a helium-burning giant star that has consumed all its [[hydrogen]] core fuel and left the main sequence, it has fully shifted to fusing [[helium]] in its core into [[carbon]] and [[oxygen]]. This stage of the star's life will only last some tens to hundreds of millions of years. Eventually the star will begin to lose its mass and the gases will puff out as a[[ planetary nebula]] containing mostly hydrogen and helium, with smaller amounts of other elements. What will be left is a [[white dwarf]] star that will gradually cool and fade over time.

There are no known substellar companions orbiting Arcturus at this time. Any world that would have been [[terrestrial planet|Earth-like]] while Arcturus was on the main sequence would have long ago been destroyed. For such a world to exist now with liquid water on its surface, it would need to be centered around 11 AU away, or between the orbital distances of [[Saturn]] and [[Uranus]] in our solar system. Such a world would be extremely difficult to detect using current methods.

[[Category:Astronomy]]

==References==
{{reflist}}

Talk:Animal

2010-02-10T15:44:34Z

BMcP: /* (extra section break inserted to help things out) */

Not qualified to improve this article, other than to make it even shorter...
the article states that animals have no cell walls. If the article means Animal CELLS have no cell walls, I'm pretty sure this is incorrect. I'm an animal, and I'm sure somethings keeping the cytoplasm in my cells!

== Are humans animals? ==

I would just change this, but since an administrator wrote it I'll discuss it here first.

For the purposes of scientific classification, an 'animal' is any living thing that fulfils certain criteria, like being multicellular, eukaryotic, ingesting other organisms for nourishment, and a few other things. According to these standards, human beings are animals. Of course there are many important ways in which we differ from other animals, but for scientific purposes these are of secondary importance to the fact that we are multicellular, eukaryotic, etc...

In the opening paragraph, which describes the scientific definition of ''animal'', it is not appropriate to say that humans do not belong in this category. From a scientific point of view, ''animal'' is a plain description of physical features and not a pejorative description of primitive behavior. [[User:Eoinc|Eoinc]] 17:28, 16 January 2010 (EST)

:Those "scientific standards" fail to distinguish between human beings and animals. When secular standards conflict with reality, one of the two must suffer. We at Conservapedia prefer to retain reality at the expense of standards which contradict the truth.

:Granted that the [[human body]] is mammalian, let us not lose sight of what sets mankind apart from animals. We need not adopt the views of [[Nietzsche]] here. Calling a person an [[animal]] is always pejorative; if liberals object to use of the term "[[redneck]]", I can't see how they can tolerate classifying [[human being]]s as animals.

:This discussion is closed, unless you want to contribute to our [[Debate Topics]].

::You acknowledge that the human body is mammalian - ie, that we are mammals. Mammals are one of many subsets of the kingdom ''animalia''. Yes, we differ from every other animal in some very important ways. But, '''for the purposes of describing the physical and biological nature''' of human beings, which is all that the scientific classification is intended to do, being multicellular and eukaryotic is of more fundamental importance than our intelligence, cultural achievements, ethics, or anything else.

:::My possession of a mammalian body no more makes me a "[[mammal]]" than your position of property and use of money makes you a "[[Capitalist]]". In my view, human society and the [[Animal kingdom]] are distinct, by virtue of the fundamental [[God]]-given differences between [[human nature]] and the mere [[instinct]] of animals, as well as the divine commandment or "blessing" to take dominion over the entire [[natural world]].

:::*"And God blessed them, and God said unto them, Be fruitful, and multiply, and replenish the earth, and subdue it: and have dominion over the fish of the sea, and over the fowl of the air, and over every living thing that moveth upon the earth." King James Version, Genesis 1:28
:::*"God blessed them and said to them, "Be fruitful and increase in number; fill the earth and subdue it. Rule over the fish of the sea and the birds of the air and over every living creature that moves on the ground." New International Version, Genesis 1:28

:::You are free to believe [[Feuerbach]]'s view that, "Man is a [[higher animal]] which developed from animals through the process of [[evolution]]." As a writer here, you are free to trace the source of this view, and to tell which scientists agree with it. But please don't assert it as [[truth]]; you might try telling us what percent of biologists or other scientists agree with it, though. --[[User:Ed Poor|Ed Poor]] [[User talk:Ed Poor|Talk]] 11:22, 20 January 2010 (EST)

::It is regrettable that you conflate the meanings of ''animal'' as a neutral term for certain types of organisms, ''animal'' as a colloquial term for non-human animals, and ''animal'' as a pejorative description for a human being who acts upon their most base impulses. As a piece of scientific terminology, no such negative connotations are intended.

::Couldn't the article have the standard scientific meaning of ''animal'', and then state that "colloquially, however, 'animal' is usually taken to mean any non-human animal...etc"? [[User:Eoinc|Eoinc]] 18:37, 16 January 2010 (EST)
::Or, you could have it the other way around, put the Biblical definitions first, and then add that the scientific definition of ''animal'' is any multicellular (etc, etc...), including humans. [[User:Eoinc|Eoinc]] 18:45, 16 January 2010 (EST)

::I find the above statements interesting considering the human bring article that is linked to says: ""Human being" is a term for a human that emphasizes the role of a human not merely as a social animal, but a thinking person." We are social animals, we by all scientific definitions are part of the animal kingdom, this article ignores the established biological taxonomies completely while taking one author's religious views as undisputed fact, when it is obviously not. That is not encyclopedic, nor is it honest. Instead it should be noted in the article that virtually all scientific classification in biology has our species as part of the animal kingdom. The reasons are clear, because we share all the basic definitions in biology of what falls into the kingdom Animalia. --[[User:BMcP|BMcP]] 19:12, 16 January 2010 (EST)

* virtually all scientific classification in biology has our species as part of the animal kingdom

Yes, that sentence should be in the article. --[[User:Ed Poor|Ed Poor]] [[User talk:Ed Poor|Talk]] 19:40, 16 January 2010 (EST)

Ian, at the risk of being pig-headed, let me point out that "the scientific definition" is merely a viewpoint of [[physical science]]. We take a broader view of [[Science]] here, including the [[social sciences]]. [[Anthropology]], [[psychology]], [[economics]], [[political science]], [[history]] and so on need not adhere to the [[naturalism]], [[atheism]], or even the [[agnosticism]] of modern liberal science.

The assumption that religious or supernatural ideas cannot or should not be studied, is not inherently scientific (see [[methodological naturalism]]). --[[User:Ed Poor|Ed Poor]] [[User talk:Ed Poor|Talk]] 21:36, 16 January 2010 (EST)

===(extra section break inserted to help things out)===
:I was a bit arrogant to "close" discussion on this point. Sorry! Let's keep talking - and not just because I have something new to say, although I admit that helped me to realize my mistake. :-)

:*Feuerbach's materialism defines the [[human being]] as a [[higher animal]] which developed from [[animal]]s through the process of [[evolution]]. [http://www.unification.org/ucbooks/cncc/cncc-02.htm]

:Conservative thought opposes this view, so on an editorial basis alone any encyclopedia would have to make its readers aware of the controversy over this point. We can't simply say that man "is an animal" on the basis of [[scientific standards]] used in [[biology]].

:Moreover, we need to explain '''why''' biologists assert that human beings are animals. Is it just because the human body is so obviously [[mammal]]ian? Or are they expressing an ideology which denies such ideas as [[life after death]], the existence of the human [[soul]] or [[spirit]], and (greatest of all) the doctrine that God created man in His image?

:There's more here than meets the eye, and I'd rather not let liberals or anyone else sweep these issues under the rug. --[[User:Ed Poor|Ed Poor]] [[User talk:Ed Poor|Talk]] 11:11, 20 January 2010 (EST)

::First I must point out that not all conservatives disagree with the evolutionary theory. I hold many conservative views and I accept fully evolution. For me conservatism is a political concept, while evolution is a concept of science. Other may disagree of course, but that I where I am coming from, I just wanted to mention this so as to be straightforward and honest in my views.

::Biologists assert human are animals based on biological definitions of what an animal is. In basic biological terms animals are eukaryotic, heterotrophic, lack rigid cell walls, are motile (even if at only certain sages of life), it is a very broad category and most people misinterpret the biological term with more colloquial (and often ill-defined) terms for the word. However humans do have all these attributes. The first person to come up with a taxonomic classification for animals was Carl Linnaeus and he place humans in that kingdom, note this was a century before the theory of evolution existed, Linnaeus was a creationist.

::In this view, souls and other metaphysical ideas are not considered as they are not part of biology. I do not object to writing about metaphysical concepts when it comes to humans (us) but those are separate subjects and should have their own entries. --[[User:BMcP|BMcP]] 15:01, 20 January 2010 (EST)

:::As a theological issue I think this matters to my work on the CBP, specifically [[Ecclesiastes_(Translated)#Chapter_3]] 18-22 please go take a look. --[[User:SamF|SamF]] 15:12, 20 January 2010 (EST)

::::Myself, I don't think the actual answer matters to Ecclesiastes, because (according to my analysis) Solomon wrote this book while he was an idolater - so he got a lot of things wrong. (Perhaps this page isn't [[Talk:Ecclesiastes|the best place to discuss this sub-topic further]]...) --[[User:EvanW|EvanW]] 15:18, 20 January 2010 (EST)

I don't know why you all keep repeating the eukaryotic bit; I wasn't ignoring you. But you seem to be missing the main point I'm making.

There is more to a person than his [[human body]], and biologists have apparently decided not to study or even acknowledge aspects of human beings which make them entirely distinct from animals. In fact, along with Feuerbach and Lenin they have ideologically chosen to assert that humans evolved naturally from animals; that's why we are animals.

We need not propagate the erroneous assumptions of biologists, or their short-sightedness. Science is more than just [[physical science]]. [[Anthropology]] and [[psychology]] are sciences, and they are by no means required to adhere to liberal, anti-religious positions such as [[methodological naturalism]].

Linneaus is free to put humans where he wants. Meanwhile, God has put us where He wants. Pick a side, my friend. --[[User:Ed Poor|Ed Poor]] [[User talk:Ed Poor|Talk]] 17:11, 22 January 2010 (EST)

:"There is more to a person than his human body, and biologists have apparently decided not to study or even acknowledge aspects of human beings which make them entirely different from animals."
::Yes, exactly. There is more to me than my body, but the study of such things doesn't fall within the remit of biology. Biologists study our biological nature, in which we are not all that different from apes and other animals; anthropologists and sociologists study other areas about us in which we are remarkably different. Sociology and anthropology add much to our understanding of our species, but they cannot tell us anything about our biological nature. It's like if we were studying a country, and some people study the history in great detail, others the geography, others the culture, others the language, etc... No one person studies the "whole thing", and it's not shortsightedness on their part; it's necessary so that we can gather as much information as we can. If we all tried to do everything, we would get a broad but shallow understanding. I think you're reading too much into it to say that scientists have some other, ulterior motive to "deny" the things that set us apart from other animals. [[User:Eoinc|Eoinc]] 10:39, 23 January 2010 (EST)

:::It depends on what scientists are saying:
:::# that the "biological nature" of human beings is that of an animal
:::# that the human body is not qualitatively different from the body of an animal
:::# that human beings are animals

:::The first statement attempts to evade being offensive, but can succeed only by being vague.
:::The second statement is acceptable.
:::The third statement smacks of Feuerbach and Lenin and apparently reflects a desire to demean people by lowering them to the level of animal or to elevate animals to the level of people (see [[animal rights advocacy]]).

:::*Although scientifically humans are animals, in everyday usage, animal often refers to any member of the animal kingdom that is not a human being, and sometimes excludes insects (although including such arthropods as crabs). The common distinction made between animals and humans likely reflects the special status people accord themselves as the pinnacle of the natural world, and indeed stewards of creation, and the fact that humans also are defined in religious, spiritual, moral, social, and psychological terms. Indeed, many religions consider humans to uniquely have a soul or spirit that remains after death of the physical body. [http://www.newworldencyclopedia.org/entry/Animal]

:::*... although there are close anatomical similarities between humans and other primates, particularly chimpanzees, the gap between humans and apes in terms of culture, mental capacity, and various spiritual, emotional, and technological aspects is so large as to dwarf differences between apes and other animals. In this sense, philosophers have recognized humans as distinct from animals generally. [http://www.newworldencyclopedia.org/entry/Human_being#Humans_as_primates]

:::I wish I could copy that, but the license isn't compatible with CP. --[[User:Ed Poor|Ed Poor]] [[User talk:Ed Poor|Talk]] 17:32, 25 January 2010 (EST)

:Well we have to remember, this is an article about the kingdom Animalia, as such it should be mentioned as far as humans go, that we are in both biologic and taxonomic classifications, animals. Any deeper notions about humanity, specifically religious, social, anthropological, psychological aspects, and so forth, should be covered instead in brief in the general article about humans and in detail in articles about humans and that specific subject.

:We are but a tiny part of the animal kingdom and in a general animal article, the mentioning about our inclusion should be brief and to the point, with internal links to articles about humans for further references and information in regards our species. --[[User:BMcP|BMcP]] 12:35, 26 January 2010 (EST)

::Are you trying to weasel out of it, or are you simply not getting the point?

::Here's a summary of the points I'm making - in no particular order (along with some new ideas, just to confuse you ;-):
::*We [[human being]]s are '''not''' part of the [[animal kingdom]], no matter what biologists say.
::*The [[human body]] is indeed [[mammal]]ian, but having the body of a mammal does not detract from our [[human nature]], i.e, the fact that we have an eternal [[soul]].
::*Biology is a field of scientific study which has boundaries, although these are perhaps ill-defined. What is "[[life]]" after all? If for human beings our threescore and ten is only the prelude to an [[eternal life]] in heaven, then should biology be studying that?
::*We have not yet merged the [[Animal]] article with the [[Animalia]] article.
::*At the risk of repeating myself, any decision by [[mainstream science]] authorities to classify man in the [[animal kingdom]] or as "an [[animal]]" is either:
::*#an illegitimate attempt to sneak past the bounds of [[biology]] into [[theology]] so they can assert ideological, materialistic points which deny spiritual [[life after death]], or
::*#a convenient way of classifying the human body (in which case we need a strong statement that any further suggestions about whether there is more to human life and the human mind than our bodies, may be outside the scope of mainstream biology)

::We need to come to terms on this issue, and not sweep it under the rug. I'm not going to be dogmatic about it, but neither will I accept the dogma of materialistic biology. --[[User:Ed Poor|Ed Poor]] [[User talk:Ed Poor|Talk]] 18:29, 28 January 2010 (EST)

:::I just want to stay on the specific topic of a general Animals article. Biology doesn't deal with the metaphysical simply for the fact that metaphysical topics are in an entirely different discipline. Biology just deals with origin, growth, reproduction, structure, and behavior of living organisms. The idea of a spiritual aspect to human beings should be covered in articles about humans, religion, and theology. This article should just be about "what is an animal". Biological definitions work for this. All that needs to be said in this article is that "According to biology, humans are a part of the animal kingdom". Have a link to humans to the human article where metaphysical ideas would fit, as there we are talking humans specifically. I am not trying to disrespect your religious beliefs, I am just pointing out such things are beyond this article's scope. --[[User:BMcP|BMcP]] 15:54, 2 February 2010 (EST)

::You just contradicted yourself. If biology should not "deal with the metaphysical", then how can it assert that humans are "part of the animal kingdom"? That is a belief, not science.

::If we knew for a fact that human beings had no metaphysical aspects (no supernatural soul, no possibility of [[life after death]], no direct relationship with a benevolent [[Creator]]), then the [[physical sciences]] would be right in classifying humans as animals. But refusing to study something doesn't make it go away.

::If science '''does not know''' whether human beings have an invisible, eternal aspect (such as the [[human mind]], the [[spirit]] or [[soul]], then it would be [[dogma]]tic for scientists to say that they do not. Worse, it would be [[pseudoscience]], because they would be asserting an idea which is not [[falsifiable]].

::The essence of [[liberal deceit]] is often to pretend that there is no controversy. Wikipedia doesn't even have an article on [[scientific debate]]. Last time I checked, it had only a redirect to [[scientific rhetoric]]. Liberals refuse to acknowledged that real scientists can have genuine disagreements, and that it can take decades or centuries to resolve issues. --[[User:Ed Poor|Ed Poor]] [[User talk:Ed Poor|Talk]] 19:16, 3 February 2010 (EST)

::: I see the problem here, you believe that in biology and taxonomy, by classifying homo sapiens (humans) as part of the animal kingdom (Animalia) that it somehow commenting on the metaphysical and supernatural, that it is inferring that humans have no souls or spirits. That is not true, we are classified as such because of our biological traits, biology as a science does not attempt to answer questions of souls or spirits, because that is outside the scope of biology (and taxonomy). It isn't considered because there is no scientific way to prove or disprove something as "a soul". Biologically we are animals because we share all the basic traits that defines an animal, really that is what this article is about. --[[User:BMcP|BMcP]] 10:44, 10 February 2010 (EST)

Algol

2010-02-09T17:27:52Z

BMcP: Added night sky template

{{Night Sky
| image =Position Beta.png
| designation =Beta Persei
| rightascension =03h 08m 10.1315s
| declination =+40o 57′ 20.332″
| distance =93 ±2 ly
| constellation =[[Perseus]]
| type =[[Binary star]]
| dimensions =
| magnitude =Absolute Mag: -0.15 Apparent Mag: 2.12
| redshift =
| radvelocity =3.7 km/s
| propmotion =RA: 2.39 mas/yr Dec.: -1.44 mas/yr
| parallax =35.14 ±0.90 mas
}}

'''Algol''', also known as '''Beta Persei''', is a triple star system located 92.8 light years away in the constellation of [[Perseus]]. A star system that has been well known throughout [[human history]], it is also the first and most well known eclipsing binary. Normally Algol's apparent magnitude is 2.1, but every 2 days, 20 hours, and 49 minutes, the magnitude drops to 3.4 for some 10 hours. This is due to Algol A (Beta Persei A) being regularly eclipsed from our point of view, by the dimmer Algol B (Beta Persei B).<ref>http://csep10.phys.utk.edu/astr162/lect/binaries/algol.html</ref>

==Algol in History==

The Algol star system was known at least since antiquity. The [[Ancient Greeks]] called Algol the "Evil eye" of [[Medusa]]. This was most likely due to the regular occurrences of the change in brightness and color as Beta Persei B eclipsed Beta Persei A. The name Algol itself is derived from the [[Arabic]] term أس الغول ''ra's al-ghūl'', meaning the Demon's Head or the Head of the Ogre. The name likely stems from the [[Greek]] view of the star system, specifically [[Ptolemy]], who named it as ''τῶν ἐν γοργονίῳº ὁ λαμπρός'', meaning "the bright one of those in the [[Gorgon|Gorgon's]] head". The names "Blinking Demon" and "Demon Star" are [[English]] translations of the Arabic name.<ref>Allen, Richard Hinckley (1963). Star Names: Their Lore and Meaning (revised edition). Dover. pp. 332–33. ISBN 0-486-21079-0. OCLC 185804232 637940</ref>

In [[Hebrew]] legend, the star was seen as ''Rōsh ha Sāṭān'' or '[[Satan|Satan's]] head'. It was also linked with the mythical [[Lilith]]. In Latin it was called ''Caput Larvae'', or 'Spectre's Head'.<ref name="penelope">http://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Perseus*.html</ref> [[Medieval]] [[Europe|Europeans]] saw Algol as one of the 15 Behenian stars used for [[astrology]].<ref>Tyson, Donald; Freake, James (1993). Three Books of Occult Philosophy. Llewellyn Worldwide. ISBN 0875428320. OCLC 26634250 41597186</ref> The [[Chinese]] named the star 大陵五, meaning the Fifth Star of the Mausoleum, although they also named it 叠尸 or ''Tseih She'', meaning 'Piled up corpses'.<ref name="penelope">http://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Perseus*.html</ref>

The first known recording of Algol's regular variation in its magnitude was in 1667 by Geminiano Montanari. In May 1783, John Goodricke presented his findings on the proposed cause of Algol's variability to the Royal Society. He believed a dark body regularly passed in front of the star, or that the star itself had some dark spot.<ref>http://www.surveyor.in-berlin.de/himmel/Bios/Goodricke-e.html</ref> It wasn't until 1881, that Edward Pickering, an astronomer from [[Harvard]], brought forth evidence that Algol was an eclipsing binary star system.<ref>http://adsabs.harvard.edu/abs/1881AReg...19..253.</ref> This was confirmed in 1889 by Hermann Carl Vogel, who discovered periodic [[Dopper Shift|Doppler shifts]] in the spectrum of Algol A and the eclipsing Algol B.<ref>http://adsabs.harvard.edu/abs/1989SSRv...50....1B</ref>

==Star System==

Algol is a triple star system. The first two [[star|stars]] make up the famous eclipsing binary and are separated from each other by a distance of only 0.062 AU. The orbit of the two stars is highly circular and take only 2.87 days to complete. From [[Earth]], the orbit is inclined at 97.69°.<ref>http://adsabs.harvard.edu/abs/1996AAS...188.6014M</ref> A third star orbits the first two at the distance of 2.69 AU, taking some 1.86 years to complete with an inclination of 83.98°.<ref>http://ad.usno.navy.mil/wds/orb6.html</ref>

===Beta Persei A===

'''Algol A''' (Beta Persei A) is a blue white main sequence dwarf star of spectral type B5-8 V, and the most massive of the triple star system. The star has a diameter 2.88 times that of our [[Sun]] with a mass 3.59 times as great.<ref name="kim">http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1989ApJ...342.1061K</ref> The star is considerably brighter than the Sun. Its visual luminosity is 98 times of the Sun, and the total luminosity though is some 200 times as great, accounting for [[ultraviolet]] [[radiation]]. Algol A rotates at a quick 65 km/sec and could possibly be less then 300 million years old.

===Beta Persei B===

'''Algol B''' (Beta Persei B) is a orange-red subgiant star of spectral class K0-2 IV. Once the most massive of the three stars of the system, it has become a cool, low-mass star that has distorted into a teardrop shape from the [[tidal force|tidal forces]] caused by its companion, Algol A. The gas from Algol B itself is being drained slowly away in an accretion stream towards its close companion, now the more massive of the two stars. Algol B itself has around 79 percent of our Sun's mass and 3.54 times its diameter. As a subgiant, the star is also 3.4 times as luminous as our Sun.<ref name="kim">http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1989ApJ...342.1061K</ref>

===Beta Persei C===

'''Algol C''' (Beta Persei C) is a blue white main sequence dwarf of spectral type A5 V. The star has 1.7 times our Sun's diameter and 1.67 times its mass. Its luminosity is around 4.1 times that of our Sun. Algol C orbits the other two stars with an average orbit of 2.69 AU.<ref name="kim">http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1989ApJ...342.1061K</ref>

For an [[terrestrial planet|Earth-like]] world to have liquid [[water]] on its surface, it would have to be around 14 AU from the three stars, or the equivalent of an orbit between [[Saturn]] and [[Uranus]]. The hypothetical world would have an orbital period of over 27 years. Because the system itself is very young, it is unlikely such a planet would have time to cool to the point of holding water.

==Algol Paradox==

The '''Algol paradox''' came about because according to the theory of [[Stellar Evolution|stellar evolution]], stars in a binary star system form at about the same time, and the more massive star will evolve more quickly then the less massive one. The paradox is a result of Algol A being more massive star of the binary pair, yet still a main sequence star, while the less massive Algol B has already reached the subgiant stage in its evolution.

Astronomers believe the paradox is explained though Algol B losing much of its [[mass]]. As Algol B swelled up into the subgiant stage, its companion star, being so close, would produce [[tide|tides]] in Algol B. Matter from Algol B's now swollen outer shell exceeded its '''Roche lobe''' (the volume where the star's gas is gravitationally bound). These outer gases would then be pulled away by the tidal forces into an accretion stream of matter that moves towards Algol A, giving Algol B a teardrop shape pointing towards its companion. As a result Algol B is losing mass at some two hundred millionths of a solar mass a year. Over time, the once massive star been reduced to 79 percent of the Sun's mass.<ref>http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1995BaltA...4...64P</ref>

[[Category:Astronomy]]

==References==
{{reflist}}

Globular cluster

2010-02-09T16:59:39Z

BMcP: Undo revision 752999 by Fanngo (Talk) Just a bunch of spam.

{{image request}}
A '''globular cluster''' is a spherical grouping of [[star|stars]] that share a common origin and orbits the galactic core of a [[galaxy]] as a satellite. They are very tightly bound by [[gravity]] and contain anywhere from tens of thousands to million of stars in an area that is only some 300 light years across or less, and are generally oblate spheroids in shape. The density of the clusters are on average around 0.4 stars per cubic [[parsec]], but increases toward to the center of the cluster, reaching as high as 100 or even a 1000 stars per cubic parsec.<ref>http://www.astro.keele.ac.uk/workx/globulars/globulars.html</ref>

Unlike [[open cluster|open clusters]], which contain [[metallicity|population I stars]] and reside in the [[galactic disk]], globular clusters are made up of population II stars and are found in either the [[galactic bulge]] or [[galactic halo]]. Some globular clusters are found as far out as 131,000 light years from the core of the galaxy.<ref>http://adsabs.harvard.edu/abs/1996A&A...313..119D</ref> Current, there are 158 known globular clusters around the [[Milky Way]], with several more perhaps yet to be discovered, all moving in highly eccentric orbits.<ref>http://www.seds.org/~spider/spider/MWGC/mwgc.html</ref> Beyond the Milky Way, most other galaxies in the Local Group and beyond have globular clusters. [[Andromeda_galaxy|Andromeda]] is known to have some 500.

==History==

Abraham Ihle, an amateur [[astronomer]] from [[Germany]] was the first to discover a globular cluster when he found the cluster M22 in 1665, however at the time his telescope was not able to resolve the individual stars. [[Charles Messier]] was the first to identify globular clusters as being made up of individual stars when he observed the cluster M4. It was [[William Herschel]] though who first coined the term globular cluster in his catalog of deep sky objects in 1789. Herschel also discovered 37 such clusters alone, as well as fully resolve the stars in 33 previous discovered ones.

In 1918, [[Harlow Shapley]] used his studies of globular clusters and their asymmetrical distribution in the galaxy to calculate both the distance of the [[Sun]] to the galactic center, and the overall dimensions of the [[Milky Way]] itself. Although the measurements he made were off from the actual size of the galaxy, due to not taking into account dust in the Milky Way diminishing light from the various clusters, he did in fact show the galaxy was much larger then previously believed.<ref>http://adsabs.harvard.edu/abs/1918PASP...30...42S</ref>

==Composition==

The stars themselves that make up globular clusters are all metal-poor population II stars, similar to those located in the central budge of the [[Milky Way]]. There is also no detectable gas or dust in these clusters.

Globular clusters are further divided into two major groupings known as ''Oosterhoff groups'', the difference between the level of [[metallicity]] found in the stars in the cluster. Clusters of the type I group are found to have somewhat weak metal absorption line in their spectra, while Type II have very weak metal lines. As such, Type I clusters are referred to as "metal-rich" and Type II as "metal-poor". Both types are metal-poor in comparison to population I stars found in the [[galactic disk]].<ref>van Albada, T. S.; Baker, Norman (1973). "On the Two Oosterhoff Groups of Globular Clusters". Astrophysical Journal 185: 477–498. do:10.1086/152434.</ref> In the Milky Way, the more metal-poor type II clusters are located in the outer part of the galactic halo, while the more metal-rich clusters are found near the galactic budge.<ref>http://adsabs.harvard.edu/abs/1976AJ.....81.1095H</ref> Both types of globular cluster populations have been found in several galaxies, being most common in large [[elliptical galaxy|elliptical galaxies]]. What causes the difference between the two types of clusters is not exactly known. Some scenarios to explain this include galaxy mergers, the absorption of satellite galaxies, and staggered star formation within galaxies.<ref>http://adsabs.harvard.edu/abs/2002astro.ph..7607Y</ref>

==Old Universe View==

In the cosmological model of a billions of years old universe, it is theorized that globular clusters are around 9 to 13 billion years in age and initially form as a loose collection of stars. The current theory in this model suggests as the cluster passes into "adolescence", the stars near the center of the cluster begin to collapse in towards each other. This collapse ends when the interaction of [[binary star|binary systems]] and prevents any further contraction, at this point the cluster is at what is referred to as "middle age". Over millions of years, the stars in the binary systems are ejected by gravitational disruption as the cluster passes through "old age". Virtually all globular clusters are theorized to be far along int the "old age" portion of their evolution. However a more recent study of 13 globular clusters suggests though that some of the clusters may actually be much younger then initially believed. From observations by the [[Chandra X-Ray Observatory]], three of the clusters were found to have a large number of [[x-ray]] binaries, suggesting to them that not enough time has passed to eject many binary companions from the cluster, if the current models are correct. If these new observations are are confirmed, this would challenge the current theories on the evolution of such clusters within the old universe cosmology.<ref>http://www.astronomynow.com/Oldglobularclusterssurprisinglyyoung.html</ref>

[[Category: Astronomy]]

==References==
{{reflist}}

Acrux

2010-02-09T16:56:54Z

BMcP: Removed {{image request}} as we have an image now.

{{Night Sky
| image =Acrux kstars.png
| designation =Alpha Crucis HD 108248
| rightascension =12h 26m 35.8958s
| declination =-63o 05' 56.73"
| distance =325 ly
| constellation =[[Crux]]
| type =[[star]]
| dimensions =
| magnitude =Apparent: 0.77 Absolute:-4.14
| redshift =
| radvelocity =-11 km/s
| propmotion =RA: -35.37 mas/yr Dec.: -14.73 mas/yr
| parallax =10.17 ± 0.67 mas
}}

'''Acrux''', also known as '''Alpha Crucis''', is the southernmost first magnitude star and the twelfth brightest star in the night sky, with an apparent magnitude of 0.77. The star is also the brightest star of the constellation [[Crux]], otherwise commonly known as the '''Southern Cross'''. Because of the star's location at 63 degrees south of the [[celestial equator]], it is not visible north of latitude 27°N. <ref name="david">http://www.daviddarling.info/encyclopedia/A/Acrux.html</ref>

==Acrux in Culture and History==

Acrux doesn't have an ancient proper name that most brighter stars have, most likely due to its far southern position. The name itself is simply a combination of the letter ''A'' in Alpha (the star's Bayer designation) and the name of the constellation it sits in, [[Crux]]. Although in [[China]], the star is known as 十字架二 (the Second Star of the Cross).

Because of the star's prominence in the southern hemisphere skies it is represented in the flags of [[Australia]], [[New Zealand]], and [[Papua New Guinea]], all three which display the stars of the Southern Cross. It star is also on the flag of [[Brazil]], representing one of the 26 states of that country, specifically the State of '''São Paulo'''.<ref name="illinois">http://stars.astro.illinois.edu/sow/acrux.html</ref>

==Star System==

Acrux itself is actually a multiple star system of three known stars, located 325 light years away. Two of the stars of the Acrux system make up a [[Binary_stars#Visual_Binaries|visual binary]], and are commonly referred to as '''Alpha-1''' and '''Alpha-2''' respectively. The two stars have a separation of at least 430 AU and take a minimum of 1500 years to complete an orbit of each other. Furthermore, Alpha-1 itself is a [[Binary_stars#Spectroscopic_Binaries|spectroscopic binary]] star. From an observer on [[Earth]], there is another star located on 90 arcseconds from the triple stars of the Acrux system and has the same proper motion in space. If this additional star is part of the system, it would have an orbital distance of 9000 AU from the other stars in the system. However it is likely the star is just an optical binary and not part of the system at all, and many be significantly more distant star that is along the same line of sight.

===Alpha Crucis A===

'''Alpha Crucis A''' or '''Alpha-1''' is actually a binary pair (Alpha Crucis Aa and Alpha Crucis Ab respectively), the binary being visible only through its spectrum. The primary star (Alpha Crucis Aa) is blue-white subgiant star of spectral type B0.5 III. Alone the star has an apparent magnitude of 1.4 and would be the 20th brightest star in the night sky.<ref name="illinois">http://stars.astro.illinois.edu/sow/acrux.html</ref> The star has 14 times the [[Sun|Sun's]] mass and is 25,000 times as visually luminous, even though most of its radiation is in the [[ultraviolet]]. The surface temperature is 28,000 K. <ref name="david">http://www.daviddarling.info/encyclopedia/A/Acrux.html</ref>

Alpha Crucis Aa and its companion orbit every 75.78 days. The orbit is eccentric, varying between 0.5 and 1.5 AU, with an average of only around 1 AU, or about the distance of the [[Sun]] from the [[Earth]].<ref name="illinois">http://stars.astro.illinois.edu/sow/acrux.html</ref> The smaller companion itself is spectral class B0, and may be 10 times as massive as the Sun.<ref>http://jumk.de/astronomie/big-stars/acrux.shtml</ref>

===Alpha Crucis B===

'''Alpha Crucis A''' or '''Alpha-2''' is a blue-white dwarf star of spectral type B1 V. The star has an apparent magnitude of 2.09, making it easily visible to the unaided eye if the star was alone. Alpha Crucis A is 13 times as massive as our [[Sun]]. Its visual luminosity 16,000 as great as the Sun's, even with most of the radiation in the [[ultraviolet]]. The surface temperature is estimated to be 26,000 K.<ref name="david">http://www.daviddarling.info/encyclopedia/A/Acrux.html</ref>

[[Category:Astronomy]]
[[Category:Double Stars]]

==References==
{{reflist}}

Achernar (star)

2010-02-09T16:52:38Z

BMcP:

{{Night Sky
| image =
| designation =Alpha Eridani HD 10144
| rightascension =01h 37m 42.85s
| declination =57o 14′ 12.3″
| distance =139 ±3 ly
| constellation =[[Eridanus]]
| type =[[Star]]
| dimensions =
| magnitude =Absolute Mag: -2.27 Apparent Mag: 0.50
| redshift =
| radvelocity =16 km/s
| propmotion =RA: 87.00 ±0.58 mas/yr Dec.: −38.24 ±0.50 mas/yr
| parallax =023.39 ±0.57 mas
}}
'''Achernar''', also known as '''Alpha Eridani''', is the brightest star of the constellation [[Eridanus]], and the ninth brightest star overall in the night sky. The [[star]] is not well known to those in the northern hemisphere, as it is only visible to those who live south of 32 degrees north latitude. South of 33 degrees south latitude, the star is [[circumpolar]].

The name Achernar, sometimes spelled as '''Achenar''', is derived from the Arabic آخر النهر ''ākhir an-nahr'', meaning "the End of the River". In Chinese though, the star is called 水委一 (''Shuǐwěiyī''), meaning "the First Star of the Crooked Running Water".<ref>Star-names and Their Meanings, Richard Hinckley Allen, New York: G. E. Stechert, 1899, p. 218</ref>

Achernar is a blue main sequence star of spectral type B3 Vpe, located 144 light years away. The star's mass is between six and eight times that of our [[Sun]],<ref name="harvard">http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1988BAICz..39..329H</ref> and 14.4 to 24 times its diameter.<ref>http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2003A%26A...407L..47D</ref> The star is 1,070 times as visually luminous as the Sun, but depending on the estimate of [[ultraviolet]] [[radiation]] the star emits, is 2,900 to 5,400 times as great as the Sun in total luminosity. Surface temperature estimates range from 14,500 to 19,300 K.
[[Image:Position Alpha Eri.png|thumb|left|154px|Location of Achernar in the constellation of Eridanus, as indicated by the pink arrow.]]
A fast-rotating star, Achernar has a spin velocity of 225 to 300 kilometers per second, completing a rotation of only 2.1 days, causing the star to eject mass at a rate thousands of times greater than our Sun. Because of this, Achernar is classified as a "Be" (B-emission) star, with an expanding circumstellar envelope of gas circulating around the [[equator]]. The tremendous speed also gives Achemar a distinct oblate spheroid shape. Its equatorial radius measures some 11.6 Suns across, while the polar radius measures only 7.5 Suns across, making the star more than 50 percent wider at the equator than at the poles.<ref name="harvard">http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1988BAICz..39..329H</ref>

Achernar is still young enough, being only a couple hundred million years old, to still be fusing [[hydrogen]] into [[helium]] in its core. It will burn through its core fuel quickly however, and eventually evolve into a large white dwarf, much like [[Sirius#Sirius_B|Sirius B]].<ref>http://stars.astro.illinois.edu/sow/achernar.html</ref>

There are no known substaller companions to Achernar. For an [[terrestrial planet|Earth-like]] to have liquid water on its surface, the hypothetical planet's orbit would be centered around 54 to 73 AUs, an orbit greater then the orbit of [[Pluto]]. At such a distance, the planet would take between 160 and 260 years to orbit Achernar.<ref>http://www.solstation.com/x-objects/achernar.htm</ref>

[[Category:Astronomy]]

==References==
{{reflist}}

Achernar (star)

2010-02-09T16:51:49Z

BMcP: Added night sky template, need to find good image for it.

{{Night Sky
| image =
| designation =Alpha Eridani HD 10144
| rightascension =01h 37m 42.85s
| declination =57o 14′ 12.3″
| distance =139 ±3 ly
| constellation =[[Eridanus]]
| type =[[Star]]
| dimensions =
| magnitude =Absolute Mag: -2.27 Apparent Mag:0.50
| redshift =
| radvelocity =16 km/s
| propmotion =RA: 87.00 ±0.58 mas/yr Dec.: −38.24 ±0.50 mas/yr
| parallax =023.39 ±0.57 mas
}}
'''Achernar''', also known as '''Alpha Eridani''', is the brightest star of the constellation [[Eridanus]], and the ninth brightest star overall in the night sky. The [[star]] is not well known to those in the northern hemisphere, as it is only visible to those who live south of 32 degrees north latitude. South of 33 degrees south latitude, the star is [[circumpolar]].

The name Achernar, sometimes spelled as '''Achenar''', is derived from the Arabic آخر النهر ''ākhir an-nahr'', meaning "the End of the River". In Chinese though, the star is called 水委一 (''Shuǐwěiyī''), meaning "the First Star of the Crooked Running Water".<ref>Star-names and Their Meanings, Richard Hinckley Allen, New York: G. E. Stechert, 1899, p. 218</ref>

Achernar is a blue main sequence star of spectral type B3 Vpe, located 144 light years away. The star's mass is between six and eight times that of our [[Sun]],<ref name="harvard">http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1988BAICz..39..329H</ref> and 14.4 to 24 times its diameter.<ref>http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2003A%26A...407L..47D</ref> The star is 1,070 times as visually luminous as the Sun, but depending on the estimate of [[ultraviolet]] [[radiation]] the star emits, is 2,900 to 5,400 times as great as the Sun in total luminosity. Surface temperature estimates range from 14,500 to 19,300 K.
[[Image:Position Alpha Eri.png|thumb|left|154px|Location of Achernar in the constellation of Eridanus, as indicated by the pink arrow.]]
A fast-rotating star, Achernar has a spin velocity of 225 to 300 kilometers per second, completing a rotation of only 2.1 days, causing the star to eject mass at a rate thousands of times greater than our Sun. Because of this, Achernar is classified as a "Be" (B-emission) star, with an expanding circumstellar envelope of gas circulating around the [[equator]]. The tremendous speed also gives Achemar a distinct oblate spheroid shape. Its equatorial radius measures some 11.6 Suns across, while the polar radius measures only 7.5 Suns across, making the star more than 50 percent wider at the equator than at the poles.<ref name="harvard">http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1988BAICz..39..329H</ref>

Achernar is still young enough, being only a couple hundred million years old, to still be fusing [[hydrogen]] into [[helium]] in its core. It will burn through its core fuel quickly however, and eventually evolve into a large white dwarf, much like [[Sirius#Sirius_B|Sirius B]].<ref>http://stars.astro.illinois.edu/sow/achernar.html</ref>

There are no known substaller companions to Achernar. For an [[terrestrial planet|Earth-like]] to have liquid water on its surface, the hypothetical planet's orbit would be centered around 54 to 73 AUs, an orbit greater then the orbit of [[Pluto]]. At such a distance, the planet would take between 160 and 260 years to orbit Achernar.<ref>http://www.solstation.com/x-objects/achernar.htm</ref>

[[Category:Astronomy]]

==References==
{{reflist}}

Metallicity

2010-02-09T16:25:37Z

BMcP: /* Old Universe View */

'''Metallicity''' is a term in [[astronomy]] that refers to the proportion of elements in an astronomical object (usually a [[star]]) that are other than [[hydrogen]] or [[helium]]. In astronomy, all elements heavier then hydrogen and helium are collectively referred to with the blanket term "metals"<ref name="metal">https://edocs.uis.edu/jmart5/www/rrlyrae/metals.htm</ref>. Therefore a star or a [[nebula]] that contained significant amounts of elements such as [[carbon]], [[oxygen]], or [[nitrogen]] would be considered "metal rich" even though those same elements are classified as nonmetals in chemistry<ref>http://www.wisegeek.com/what-is-metallicity.htm</ref>.

Usually, metallicity is expressed in terms of the relative amounts of [[iron]] and hydrogen present in a star, since iron is among the easiest elements to measure with spectral data in the visible spectrum. This is determined by analyzing absorption lines in a stellar spectrum using a spectrometer, compared to the star's solar value. The ratio of the amount of iron to the amount of hydrogen in the object is divided by the ratio of the amount of iron to the amount of hydrogen in the Sun (which has a metallicity of 1.6 percent by mass). This value, expressed as [Fe/H], is calculated using the following logarithmic formula<ref name="metal">https://edocs.uis.edu/jmart5/www/rrlyrae/metals.htm</ref>.

<center><math> [\mathrm{Fe}/\mathrm{H}] = \log_{10}{\left(\frac{N_{\mathrm{Fe}}}{N_{\mathrm{H}}}\right)_{star}} - \log_{10}{\left(\frac{N_{\mathrm{Fe}}}{N_{\mathrm{H}}}\right)_{sun}} </math></center>

Where ''N''Fe and ''N''H is the number of iron and hydrogen atoms per unit of volume respectively. Using this formula, a star that has a higher metallicity then our [[Sun]] will have a positive logarithmic value, while any star with a lower metallicity then our sun will result in a negative value. Because the logarithm is based on powers of ten; a star with a value of [Fe/H] = -1 will have an abundance of heavy elements (metallicity) one tenth of that of our sun, while a value of [Fe/H] =+1 represents a star with ten times the abundance of heavy elements of our sun. Measurements of thousands of stars have resulted in a generally established range from -4 (extremely metal-poor) to +1 (very metal-rich).

==Types of stars according to Metallicity==

'''Population I stars''' are stars that are considered to be the most metal-rich (or highest metallicity), our sun falls into this category. Although such stars may be as metal-poor as >-1 in comparison to the sun, many have more metallicity then our own sun. Such stars tend to be found either in, or near the plane of a spiral galaxy such as our own [[Milky Way]]. Some of these stars are referred to as ''Extreme Population I stars'', found in the spiral arms, class O and B stars, T Tauri stars and other stars just entering the main sequence of stellar evolution are counted among these stars<ref>http://www.daviddarling.info/encyclopedia/P/PopI.html</ref>.

'''Population II stars''' are metal-poor stars (negative values beyond -1), usually located in the bulge near to the center of spiral galaxies as well as the galactic halo. Such stars are also common in Globular Clusters and make up the overwhelming number of the stellar population in elliptical galaxies. These stars are the reasoned source of most of the elements in the periodic table<ref>http://www.daviddarling.info/encyclopedia/P/PopII.html</ref>.

'''Population III stars''' are essentially metal-free stars, although some have metals at the end of their lives. Population III stars were considered to be extremely massive and hot but have not been directly observed. Indirect evidence of their existence has been found through looking at [[General theory of relativity|gravitationally lensed]]<ref>http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2002ApJ...567..532H</ref>, and distant faint blue galaxies in the very distant universe<ref>http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2003ApJ...596..797F</ref>.

==Old Universe View==

In the cosmological model of a billions of years old universe, it is theorized that the metallicity of certain astronomical objects may offer clues to those objects' ages. According to their [[Big Bang|Big Bang theory]], when the universe first formed, it consisted mostly of hydrogen with a sizable proportion of helium; only trace amounts of [[lithium]] and [[beryllium]] are believed to have been created, with no heavier elements forming. In this model, older stars will have lower metallicity than younger stars, as all other elements were created through stellar and supernova nucleosynthesis. In this model, stars classified as population III stars are the oldest known stars, followed by population II stars, and finally population I stars, which are the youngest.

[[Category:Astronomy]]

==References==
{{reflist}}

Metallicity

2010-02-09T16:14:07Z

BMcP: /* Old Universe View */

'''Metallicity''' is a term in [[astronomy]] that refers to the proportion of elements in an astronomical object (usually a [[star]]) that are other than [[hydrogen]] or [[helium]]. In astronomy, all elements heavier then hydrogen and helium are collectively referred to with the blanket term "metals"<ref name="metal">https://edocs.uis.edu/jmart5/www/rrlyrae/metals.htm</ref>. Therefore a star or a [[nebula]] that contained significant amounts of elements such as [[carbon]], [[oxygen]], or [[nitrogen]] would be considered "metal rich" even though those same elements are classified as nonmetals in chemistry<ref>http://www.wisegeek.com/what-is-metallicity.htm</ref>.

Usually, metallicity is expressed in terms of the relative amounts of [[iron]] and hydrogen present in a star, since iron is among the easiest elements to measure with spectral data in the visible spectrum. This is determined by analyzing absorption lines in a stellar spectrum using a spectrometer, compared to the star's solar value. The ratio of the amount of iron to the amount of hydrogen in the object is divided by the ratio of the amount of iron to the amount of hydrogen in the Sun (which has a metallicity of 1.6 percent by mass). This value, expressed as [Fe/H], is calculated using the following logarithmic formula<ref name="metal">https://edocs.uis.edu/jmart5/www/rrlyrae/metals.htm</ref>.

<center><math> [\mathrm{Fe}/\mathrm{H}] = \log_{10}{\left(\frac{N_{\mathrm{Fe}}}{N_{\mathrm{H}}}\right)_{star}} - \log_{10}{\left(\frac{N_{\mathrm{Fe}}}{N_{\mathrm{H}}}\right)_{sun}} </math></center>

Where ''N''Fe and ''N''H is the number of iron and hydrogen atoms per unit of volume respectively. Using this formula, a star that has a higher metallicity then our [[Sun]] will have a positive logarithmic value, while any star with a lower metallicity then our sun will result in a negative value. Because the logarithm is based on powers of ten; a star with a value of [Fe/H] = -1 will have an abundance of heavy elements (metallicity) one tenth of that of our sun, while a value of [Fe/H] =+1 represents a star with ten times the abundance of heavy elements of our sun. Measurements of thousands of stars have resulted in a generally established range from -4 (extremely metal-poor) to +1 (very metal-rich).

==Types of stars according to Metallicity==

'''Population I stars''' are stars that are considered to be the most metal-rich (or highest metallicity), our sun falls into this category. Although such stars may be as metal-poor as >-1 in comparison to the sun, many have more metallicity then our own sun. Such stars tend to be found either in, or near the plane of a spiral galaxy such as our own [[Milky Way]]. Some of these stars are referred to as ''Extreme Population I stars'', found in the spiral arms, class O and B stars, T Tauri stars and other stars just entering the main sequence of stellar evolution are counted among these stars<ref>http://www.daviddarling.info/encyclopedia/P/PopI.html</ref>.

'''Population II stars''' are metal-poor stars (negative values beyond -1), usually located in the bulge near to the center of spiral galaxies as well as the galactic halo. Such stars are also common in Globular Clusters and make up the overwhelming number of the stellar population in elliptical galaxies. These stars are the reasoned source of most of the elements in the periodic table<ref>http://www.daviddarling.info/encyclopedia/P/PopII.html</ref>.

'''Population III stars''' are essentially metal-free stars, although some have metals at the end of their lives. Population III stars were considered to be extremely massive and hot but have not been directly observed. Indirect evidence of their existence has been found through looking at [[General theory of relativity|gravitationally lensed]]<ref>http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2002ApJ...567..532H</ref>, and distant faint blue galaxies in the very distant universe<ref>http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2003ApJ...596..797F</ref>.

==Old Universe View==

In the cosmological model of a billions of years old universe, it is theorized that the metallicity of certain astronomical objects may offer clues to those objects' ages. According to their [[Big Bang|Big Bang theory]], when the universe first formed, it consisted mostly of hydrogen with a sizable proportion of helium; only trace amounts of [[lithium]] and [[beryllium]] are believed to have been created, with no heavier elements forming. In this model, older stars will have lower metallicity than younger stars, as all other elements were created through stellar and supernova nucleosynthesis.

[[Category:Astronomy]]

==References==
{{reflist}}

Globular cluster

2010-02-09T16:11:03Z

BMcP: /* Old Universe View */ Grammar fix

Globular cluster

2010-02-09T16:01:16Z

BMcP: /* Old Universe View */Repeating "old universe" is redundent with section title, evolutionist is inaccurate, orthodoxy has religious connotations

{{image request}}
A '''globular cluster''' is a spherical grouping of [[star|stars]] that share a common origin and orbits the galactic core of a [[galaxy]] as a satellite. They are very tightly bound by [[gravity]] and contain anywhere from tens of thousands to million of stars in an area that is only some 300 light years across or less, and are generally oblate spheroids in shape. The density of the clusters are on average around 0.4 stars per cubic [[parsec]], but increases toward to the center of the cluster, reaching as high as 100 or even a 1000 stars per cubic parsec.<ref>http://www.astro.keele.ac.uk/workx/globulars/globulars.html</ref>

Unlike [[open cluster|open clusters]], which contain [[metallicity|population I stars]] and reside in the [[galactic disk]], globular clusters are made up of population II stars and are found in either the [[galactic bulge]] or [[galactic halo]]. Some globular clusters are found as far out as 131,000 light years from the core of the galaxy.<ref>http://adsabs.harvard.edu/abs/1996A&A...313..119D</ref> Current, there are 158 known globular clusters around the [[Milky Way]], with several more perhaps yet to be discovered, all moving in highly eccentric orbits.<ref>http://www.seds.org/~spider/spider/MWGC/mwgc.html</ref> Beyond the Milky Way, most other galaxies in the Local Group and beyond have globular clusters. [[Andromeda_galaxy|Andromeda]] is known to have some 500.

==History==

Abraham Ihle, an amateur [[astronomer]] from [[Germany]] was the first to discover a globular cluster when he found the cluster M22 in 1665, however at the time his telescope was not able to resolve the individual stars. [[Charles Messier]] was the first to identify globular clusters as being made up of individual stars when he observed the cluster M4. It was [[William Herschel]] though who first coined the term globular cluster in his catalog of deep sky objects in 1789. Herschel also discovered 37 such clusters alone, as well as fully resolve the stars in 33 previous discovered ones.

In 1918, [[Harlow Shapley]] used his studies of globular clusters and their asymmetrical distribution in the galaxy to calculate both the distance of the [[Sun]] to the galactic center, and the overall dimensions of the [[Milky Way]] itself. Although the measurements he made were off from the actual size of the galaxy, due to not taking into account dust in the Milky Way diminishing light from the various clusters, he did in fact show the galaxy was much larger then previously believed.<ref>http://adsabs.harvard.edu/abs/1918PASP...30...42S</ref>

==Composition==

The stars themselves that make up globular clusters are all metal-poor population II stars, similar to those located in the central budge of the [[Milky Way]]. There is also no detectable gas or dust in these clusters.

Globular clusters are further divided into two major groupings known as ''Oosterhoff groups'', the difference between the level of [[metallicity]] found in the stars in the cluster. Clusters of the type I group are found to have somewhat weak metal absorption line in their spectra, while Type II have very weak metal lines. As such, Type I clusters are referred to as "metal-rich" and Type II as "metal-poor". Both types are metal-poor in comparison to population I stars found in the [[galactic disk]].<ref>van Albada, T. S.; Baker, Norman (1973). "On the Two Oosterhoff Groups of Globular Clusters". Astrophysical Journal 185: 477–498. do:10.1086/152434.</ref> In the Milky Way, the more metal-poor type II clusters are located in the outer part of the galactic halo, while the more metal-rich clusters are found near the galactic budge.<ref>http://adsabs.harvard.edu/abs/1976AJ.....81.1095H</ref> Both types of globular cluster populations have been found in several galaxies, being most common in large [[elliptical galaxy|elliptical galaxies]]. What causes the difference between the two types of clusters is not exactly known. Some scenarios to explain this include galaxy mergers, the absorption of satellite galaxies, and staggered star formation within galaxies.<ref>http://adsabs.harvard.edu/abs/2002astro.ph..7607Y</ref>

==Old Universe View==

n the cosmological model of a billions of years old universe, it is theorized that globular clusters are around 9 to 13 billion years in age and initially form as a loose collection of stars. The current theory in this model suggests as the cluster passes into "adolescence", the stars near the center of the cluster begin to collapse in towards each other. This collapse ends when the interaction of [[binary star|binary systems]] and prevents any further contraction, at this point the cluster is at what is referred to as "middle age". Over millions of years, the stars in the binary systems are ejected by gravitational disruption as the cluster passes through "old age". Virtually all globular clusters are theorized to be far along int the "old age" portion of their evolution. However a more recent study of 13 globular clusters suggests though that some of the clusters may actually be much younger then initially believed. From observations by the [[Chandra X-Ray Observatory]], three of the clusters were found to have a large number of [[x-ray]] binaries, suggesting to them that not enough time has passed to eject many binary companions from the cluster, if the current models are correct. If these new observations are are confirmed, this would challenge the current theories on the evolution of such clusters within the old universe cosmology.<ref>http://www.astronomynow.com/Oldglobularclusterssurprisinglyyoung.html</ref>

[[Category: Astronomy]]

==References==
{{reflist}}

Globular cluster

2010-02-09T15:48:53Z

BMcP: /* Composition */ Internal link for Milky Way

{{image request}}
A '''globular cluster''' is a spherical grouping of [[star|stars]] that share a common origin and orbits the galactic core of a [[galaxy]] as a satellite. They are very tightly bound by [[gravity]] and contain anywhere from tens of thousands to million of stars in an area that is only some 300 light years across or less, and are generally oblate spheroids in shape. The density of the clusters are on average around 0.4 stars per cubic [[parsec]], but increases toward to the center of the cluster, reaching as high as 100 or even a 1000 stars per cubic parsec.<ref>http://www.astro.keele.ac.uk/workx/globulars/globulars.html</ref>

Unlike [[open cluster|open clusters]], which contain [[metallicity|population I stars]] and reside in the [[galactic disk]], globular clusters are made up of population II stars and are found in either the [[galactic bulge]] or [[galactic halo]]. Some globular clusters are found as far out as 131,000 light years from the core of the galaxy.<ref>http://adsabs.harvard.edu/abs/1996A&A...313..119D</ref> Current, there are 158 known globular clusters around the [[Milky Way]], with several more perhaps yet to be discovered, all moving in highly eccentric orbits.<ref>http://www.seds.org/~spider/spider/MWGC/mwgc.html</ref> Beyond the Milky Way, most other galaxies in the Local Group and beyond have globular clusters. [[Andromeda_galaxy|Andromeda]] is known to have some 500.

==History==

Abraham Ihle, an amateur [[astronomer]] from [[Germany]] was the first to discover a globular cluster when he found the cluster M22 in 1665, however at the time his telescope was not able to resolve the individual stars. [[Charles Messier]] was the first to identify globular clusters as being made up of individual stars when he observed the cluster M4. It was [[William Herschel]] though who first coined the term globular cluster in his catalog of deep sky objects in 1789. Herschel also discovered 37 such clusters alone, as well as fully resolve the stars in 33 previous discovered ones.

In 1918, [[Harlow Shapley]] used his studies of globular clusters and their asymmetrical distribution in the galaxy to calculate both the distance of the [[Sun]] to the galactic center, and the overall dimensions of the [[Milky Way]] itself. Although the measurements he made were off from the actual size of the galaxy, due to not taking into account dust in the Milky Way diminishing light from the various clusters, he did in fact show the galaxy was much larger then previously believed.<ref>http://adsabs.harvard.edu/abs/1918PASP...30...42S</ref>

==Composition==

The stars themselves that make up globular clusters are all metal-poor population II stars, similar to those located in the central budge of the [[Milky Way]]. There is also no detectable gas or dust in these clusters.

Globular clusters are further divided into two major groupings known as ''Oosterhoff groups'', the difference between the level of [[metallicity]] found in the stars in the cluster. Clusters of the type I group are found to have somewhat weak metal absorption line in their spectra, while Type II have very weak metal lines. As such, Type I clusters are referred to as "metal-rich" and Type II as "metal-poor". Both types are metal-poor in comparison to population I stars found in the [[galactic disk]].<ref>van Albada, T. S.; Baker, Norman (1973). "On the Two Oosterhoff Groups of Globular Clusters". Astrophysical Journal 185: 477–498. do:10.1086/152434.</ref> In the Milky Way, the more metal-poor type II clusters are located in the outer part of the galactic halo, while the more metal-rich clusters are found near the galactic budge.<ref>http://adsabs.harvard.edu/abs/1976AJ.....81.1095H</ref> Both types of globular cluster populations have been found in several galaxies, being most common in large [[elliptical galaxy|elliptical galaxies]]. What causes the difference between the two types of clusters is not exactly known. Some scenarios to explain this include galaxy mergers, the absorption of satellite galaxies, and staggered star formation within galaxies.<ref>http://adsabs.harvard.edu/abs/2002astro.ph..7607Y</ref>

==Old Universe View==

Those who believe in a universe millions or billions of years old also believe that Population I stars are younger, and that the less metallicity a star has, the older it is. They believe globular clusters to be around 9 to 13 billion years in age and initially form as a loose collection of stars. They think that as the cluster passes into "adolescence", the stars near the center of the cluster begin to collapse in towards each other. This collapse, according to Old-Universe advocates, ends when the interaction of [[binary star|binary systems]] and prevents any further contraction, at this point the cluster is at what evolutionists call "middle age". Over millions of years, these Old-Universe advocates believe that stars in the binary systems are ejected by gravitational disruption as the cluster passes through "old age". Virtually all globular clusters are far along into what evolutionists call the "old age" portion of their evolution. However a more recent study of 13 globular clusters suggests though that some of the clusters may actually be much younger then initially believed. Old-Universe enthusiasts believe this is because three of the clusters were found to still have a large number of [[x-ray]] binaries, suggesting to them that not enough time has passed to eject many binary companions from the cluster. If these new observations are adopted into the Old-Universe orthodoxy, this would challenge the current theories on the evolution of such clusters.<ref>http://www.astronomynow.com/Oldglobularclusterssurprisinglyyoung.html</ref>

[[Category: Astronomy]]

==References==
{{reflist}}

Open cluster

2010-02-09T15:36:23Z

BMcP: /* Old Universe View */ Model is more accurate then belief, the latter implies faith over theory. Repeating belief is also redundent as the whole thing is within the "old Universe View" section now.

{{image request}}
An '''open cluster''', sometimes referred to as an '''open star cluster''' or a '''galactic cluster''', is a group of physically related [[star|stars]] that have similar chemical composition held together by mutual [[gravity]]. In contrast to a [[globular cluster|globular clusters]], the stars of an open cluster are only loosely gravitationally bound to each other. Open clusters have only been observed in galaxies with active star formation, such as [[spiral galaxy|spiral]] and [[irregular galaxy|irregular galaxies]], for spiral galaxies, they are found within the spiral arms.<ref>http://adsabs.harvard.edu/abs/1979stcl.book.....P</ref> These clusters are made up of [[metallicity|population I stars]]. Some clusters may still be contained in interstellar clouds, illuminating the clouds.<ref>http://adsabs.harvard.edu/abs/1962ApJ...136.1135J</ref> At current count, there are over 1,100 known open clusters in the [[Milky Way]] alone, although this may be only a small percentage of the total.<ref name="am">http://www.maa.clell.de/Messier/open.html</ref>

The clusters themselves range from large conglomerates of thousands of stars to sparse clusters of only a dozen or less. The core or center of these clusters are a few light years across with an average density of a star per 1.5 cubic light years, about 500 times as dense as our solar neighborhood.

==History of Observation==

Open clusters have been known since [[antiquity]], although before the [[telescope]] the individual stars could not be resolved and they appeared as dim patches of light. One exception to this is the most well-known open cluster, the [[Pleiades]], which was easily observable as a group of similar stars, another known cluster was the [[Hyades]], the closest open cluster to us at only 150 [[light year|light years]].

Although there are various recording of the related stars of open clusters as far back as [[Ptolemy]] in 138 A.D, it wasn't until 1767 that the stars were recognized as such when [[Reverend]] [[John Michell]] first postulated that the stars of an open clusters had to be related because the chance of finding even one such cluster if they just happen to be a collection of unrelated stars were too astronomical.<ref name="am">http://www.maa.clell.de/Messier/open.html</ref> It wasn't until 1869 that the relation of stars in an open cluster was conclusively shown. That year Richard Proctor in his study of the Pleiades and the [[Ursa Major|Ursa Major Moving Cluster]], demonstrated using spectroscopy that the stars of the clusters have the same [[radial velocity]], indicating they are bound to each other by gravity. Proctor also showed that the stars of such clusters were all about the same distance from the [[Earth]], further showing they were moving together and were related.<ref>http://adsabs.harvard.edu/cgi-bin/bib_query?1869RSPS...18..169P</ref>

==Classification==

In 1930, Swiss-American astronomer R.J Trumpler introduced a classification system for open clusters, later known as the ''Trumpler classification'', based on three defining attributes.<ref>http://books.google.com/books?id=40JzBYGREL0C&pg=PA74&dq=%22Trumpler+classification%22&ei=bMLDSLHnD5TqjgHkqeTrDQ&sig=ACfU3U0fxdckqWt_w6eawA44vGIJmi2yJg#v=onepage&q=%22Trumpler%20classification%22&f=false</ref> The first attribute is according to how concentrated the cluster is towards it's center, ranging from I-IV:

*I - Detached from the surrounding stars with strong concentration towards the cluster center
*II - Detached from the surrounding stars with weak concentration towards the cluster center
*III - Detached from the surrounding stars with no concentration towards the cluster center
*IV - Not well detached from surrounding stars

The second attribute is the range in luminosity or brightness of the member stars of the cluster, ranging from 1 to 3:

*1 - Small range in brightness in the stars of the cluster
*2 - Medium range in brightness in the stars of the cluster
*3 - Large range in brightness in the stars of the cluster

The third attribute is based on the number of stars in the cluster, referred to its ''richness'':

*p - Cluster has less then 50 stars, thus poor
*m - Cluster has between 50 and 100 stars, moderately rich
*r - Cluster has over 100 stars, rich

If the cluster lies within a [[nebula|nebulous structure]] it's classification is appended with an 'n'. Under this classification method for example, the [[Pleiades]] is classified as '''I3rn''' (Strong concentration towards the center, richly populated with stars that have a wide range in brightness, with nebulous material present). <ref>http://adsabs.harvard.edu/cgi-bin/bib_query?1930LicOB.420..154T</ref>

==Old Universe View==

In the cosmological model of a billions of years old universe it is theorized that clusters are initially formed when a large molecular cloud collapses due to nearby gravitational interactions or [[supernova]]. As the molecular cloud collapses, it will fragment into increasingly smaller parts; they think that some of these fragments of gas and material that eventually result [[stellar evolution|in the creation of new stars]]. Eventually, according to these theories, the hottest and most massive of these stars drive away the remaining gasses through their stellar winds and radiation and star formation ceases.<ref>http://adsabs.harvard.edu/abs/1991MNRAS.249...76B</ref>

As an open cluster drifts through space, the individual stars of the loosely bound cluster slowly begin to drift away from the cluster due to gravitational interactions with the rest of the galaxy. After few hundred million years the cluster would lose most of the member stars, which become individual stars orbiting the core of a [[galaxy]], connected only by their similar orbits in a disassociated group.<ref>http://adsabs.harvard.edu/abs/1998PASP..110.1117D</ref>

[[Category:Astronomy]]

==References==
{{reflist}}

{{Template:Stars}}

Open cluster

2010-02-09T15:15:01Z

BMcP: /* Classification */ "Poor" is less than 50 stars, not 5.

{{image request}}
An '''open cluster''', sometimes referred to as an '''open star cluster''' or a '''galactic cluster''', is a group of physically related [[star|stars]] that have similar chemical composition held together by mutual [[gravity]]. In contrast to a [[globular cluster|globular clusters]], the stars of an open cluster are only loosely gravitationally bound to each other. Open clusters have only been observed in galaxies with active star formation, such as [[spiral galaxy|spiral]] and [[irregular galaxy|irregular galaxies]], for spiral galaxies, they are found within the spiral arms.<ref>http://adsabs.harvard.edu/abs/1979stcl.book.....P</ref> These clusters are made up of [[metallicity|population I stars]]. Some clusters may still be contained in interstellar clouds, illuminating the clouds.<ref>http://adsabs.harvard.edu/abs/1962ApJ...136.1135J</ref> At current count, there are over 1,100 known open clusters in the [[Milky Way]] alone, although this may be only a small percentage of the total.<ref name="am">http://www.maa.clell.de/Messier/open.html</ref>

The clusters themselves range from large conglomerates of thousands of stars to sparse clusters of only a dozen or less. The core or center of these clusters are a few light years across with an average density of a star per 1.5 cubic light years, about 500 times as dense as our solar neighborhood.

==History of Observation==

Open clusters have been known since [[antiquity]], although before the [[telescope]] the individual stars could not be resolved and they appeared as dim patches of light. One exception to this is the most well-known open cluster, the [[Pleiades]], which was easily observable as a group of similar stars, another known cluster was the [[Hyades]], the closest open cluster to us at only 150 [[light year|light years]].

Although there are various recording of the related stars of open clusters as far back as [[Ptolemy]] in 138 A.D, it wasn't until 1767 that the stars were recognized as such when [[Reverend]] [[John Michell]] first postulated that the stars of an open clusters had to be related because the chance of finding even one such cluster if they just happen to be a collection of unrelated stars were too astronomical.<ref name="am">http://www.maa.clell.de/Messier/open.html</ref> It wasn't until 1869 that the relation of stars in an open cluster was conclusively shown. That year Richard Proctor in his study of the Pleiades and the [[Ursa Major|Ursa Major Moving Cluster]], demonstrated using spectroscopy that the stars of the clusters have the same [[radial velocity]], indicating they are bound to each other by gravity. Proctor also showed that the stars of such clusters were all about the same distance from the [[Earth]], further showing they were moving together and were related.<ref>http://adsabs.harvard.edu/cgi-bin/bib_query?1869RSPS...18..169P</ref>

==Classification==

In 1930, Swiss-American astronomer R.J Trumpler introduced a classification system for open clusters, later known as the ''Trumpler classification'', based on three defining attributes.<ref>http://books.google.com/books?id=40JzBYGREL0C&pg=PA74&dq=%22Trumpler+classification%22&ei=bMLDSLHnD5TqjgHkqeTrDQ&sig=ACfU3U0fxdckqWt_w6eawA44vGIJmi2yJg#v=onepage&q=%22Trumpler%20classification%22&f=false</ref> The first attribute is according to how concentrated the cluster is towards it's center, ranging from I-IV:

*I - Detached from the surrounding stars with strong concentration towards the cluster center
*II - Detached from the surrounding stars with weak concentration towards the cluster center
*III - Detached from the surrounding stars with no concentration towards the cluster center
*IV - Not well detached from surrounding stars

The second attribute is the range in luminosity or brightness of the member stars of the cluster, ranging from 1 to 3:

*1 - Small range in brightness in the stars of the cluster
*2 - Medium range in brightness in the stars of the cluster
*3 - Large range in brightness in the stars of the cluster

The third attribute is based on the number of stars in the cluster, referred to its ''richness'':

*p - Cluster has less then 50 stars, thus poor
*m - Cluster has between 50 and 100 stars, moderately rich
*r - Cluster has over 100 stars, rich

If the cluster lies within a [[nebula|nebulous structure]] it's classification is appended with an 'n'. Under this classification method for example, the [[Pleiades]] is classified as '''I3rn''' (Strong concentration towards the center, richly populated with stars that have a wide range in brightness, with nebulous material present). <ref>http://adsabs.harvard.edu/cgi-bin/bib_query?1930LicOB.420..154T</ref>

==Old Universe View==

Those who believe the Universe is millions or billions of years old often also believe that open clusters are initially formed when a large molecular cloud collapses due to nearby gravitational interactions or [[supernova]]. They believe that as the cloud collapses, it will fragment into increasingly smaller parts; they think that some of these fragments of gas and material that eventually result [[stellar evolution|in the creation of new stars]]. Eventually, according to these theories, the hottest and most massive of these stars drive away the remaining gasses through their stellar winds and radiation and star formation ceases.<ref>http://adsabs.harvard.edu/abs/1991MNRAS.249...76B</ref>

As an open cluster drifts through space, they believe, the individual stars of the loosely bound cluster slowly begin to drift away due to gravitational interactions with the rest of the galaxy. They believe that after few hundred million years the cluster would lose most of the member stars as individual stars orbiting the core of a [[galaxy]], connected only by their similar orbits in a disassociated group.<ref>http://adsabs.harvard.edu/abs/1998PASP..110.1117D</ref>

[[Category:Astronomy]]

==References==
{{reflist}}

{{Template:Stars}}

Open cluster

2010-02-09T15:10:08Z

BMcP: /* Classification */ A little more on Trumpler, added the name of the system.

{{image request}}
An '''open cluster''', sometimes referred to as an '''open star cluster''' or a '''galactic cluster''', is a group of physically related [[star|stars]] that have similar chemical composition held together by mutual [[gravity]]. In contrast to a [[globular cluster|globular clusters]], the stars of an open cluster are only loosely gravitationally bound to each other. Open clusters have only been observed in galaxies with active star formation, such as [[spiral galaxy|spiral]] and [[irregular galaxy|irregular galaxies]], for spiral galaxies, they are found within the spiral arms.<ref>http://adsabs.harvard.edu/abs/1979stcl.book.....P</ref> These clusters are made up of [[metallicity|population I stars]]. Some clusters may still be contained in interstellar clouds, illuminating the clouds.<ref>http://adsabs.harvard.edu/abs/1962ApJ...136.1135J</ref> At current count, there are over 1,100 known open clusters in the [[Milky Way]] alone, although this may be only a small percentage of the total.<ref name="am">http://www.maa.clell.de/Messier/open.html</ref>

The clusters themselves range from large conglomerates of thousands of stars to sparse clusters of only a dozen or less. The core or center of these clusters are a few light years across with an average density of a star per 1.5 cubic light years, about 500 times as dense as our solar neighborhood.

==History of Observation==

Open clusters have been known since [[antiquity]], although before the [[telescope]] the individual stars could not be resolved and they appeared as dim patches of light. One exception to this is the most well-known open cluster, the [[Pleiades]], which was easily observable as a group of similar stars, another known cluster was the [[Hyades]], the closest open cluster to us at only 150 [[light year|light years]].

Although there are various recording of the related stars of open clusters as far back as [[Ptolemy]] in 138 A.D, it wasn't until 1767 that the stars were recognized as such when [[Reverend]] [[John Michell]] first postulated that the stars of an open clusters had to be related because the chance of finding even one such cluster if they just happen to be a collection of unrelated stars were too astronomical.<ref name="am">http://www.maa.clell.de/Messier/open.html</ref> It wasn't until 1869 that the relation of stars in an open cluster was conclusively shown. That year Richard Proctor in his study of the Pleiades and the [[Ursa Major|Ursa Major Moving Cluster]], demonstrated using spectroscopy that the stars of the clusters have the same [[radial velocity]], indicating they are bound to each other by gravity. Proctor also showed that the stars of such clusters were all about the same distance from the [[Earth]], further showing they were moving together and were related.<ref>http://adsabs.harvard.edu/cgi-bin/bib_query?1869RSPS...18..169P</ref>

==Classification==

In 1930, Swiss-American astronomer R.J Trumpler introduced a classification system for open clusters, later known as the ''Trumpler classification'', based on three defining attributes.<ref>http://books.google.com/books?id=40JzBYGREL0C&pg=PA74&dq=%22Trumpler+classification%22&ei=bMLDSLHnD5TqjgHkqeTrDQ&sig=ACfU3U0fxdckqWt_w6eawA44vGIJmi2yJg#v=onepage&q=%22Trumpler%20classification%22&f=false</ref> The first attribute is according to how concentrated the cluster is towards it's center, ranging from I-IV:

*I - Detached from the surrounding stars with strong concentration towards the cluster center
*II - Detached from the surrounding stars with weak concentration towards the cluster center
*III - Detached from the surrounding stars with no concentration towards the cluster center
*IV - Not well detached from surrounding stars

The second attribute is the range in luminosity or brightness of the member stars of the cluster, ranging from 1 to 3:

*1 - Small range in brightness in the stars of the cluster
*2 - Medium range in brightness in the stars of the cluster
*3 - Large range in brightness in the stars of the cluster

The third attribute is based on the number of stars in the cluster, referred to its ''richness'':

*p - Cluster has less then 5 stars, thus poor
*m - Cluster has between 50 and 100 stars, moderately rich
*r - Cluster has over 100 stars, rich

If the cluster lies within a [[nebula|nebulous structure]] it's classification is appended with an 'n'. Under this classification method for example, the [[Pleiades]] is classified as '''I3rn''' (Strong concentration towards the center, richly populated with stars that have a wide range in brightness, with nebulous material present). <ref>http://adsabs.harvard.edu/cgi-bin/bib_query?1930LicOB.420..154T</ref>

==Old Universe View==

Those who believe the Universe is millions or billions of years old often also believe that open clusters are initially formed when a large molecular cloud collapses due to nearby gravitational interactions or [[supernova]]. They believe that as the cloud collapses, it will fragment into increasingly smaller parts; they think that some of these fragments of gas and material that eventually result [[stellar evolution|in the creation of new stars]]. Eventually, according to these theories, the hottest and most massive of these stars drive away the remaining gasses through their stellar winds and radiation and star formation ceases.<ref>http://adsabs.harvard.edu/abs/1991MNRAS.249...76B</ref>

As an open cluster drifts through space, they believe, the individual stars of the loosely bound cluster slowly begin to drift away due to gravitational interactions with the rest of the galaxy. They believe that after few hundred million years the cluster would lose most of the member stars as individual stars orbiting the core of a [[galaxy]], connected only by their similar orbits in a disassociated group.<ref>http://adsabs.harvard.edu/abs/1998PASP..110.1117D</ref>

[[Category:Astronomy]]

==References==
{{reflist}}

Open cluster

2010-02-09T14:49:12Z

BMcP: /* History of Observation */ Should be "radial velocity" not "radical velocity", fixes link.

{{image request}}
An '''open cluster''', sometimes referred to as an '''open star cluster''' or a '''galactic cluster''', is a group of physically related [[star|stars]] that have similar chemical composition held together by mutual [[gravity]]. In contrast to a [[globular cluster|globular clusters]], the stars of an open cluster are only loosely gravitationally bound to each other. Open clusters have only been observed in galaxies with active star formation, such as [[spiral galaxy|spiral]] and [[irregular galaxy|irregular galaxies]], for spiral galaxies, they are found within the spiral arms.<ref>http://adsabs.harvard.edu/abs/1979stcl.book.....P</ref> These clusters are made up of [[metallicity|population I stars]]. Some clusters may still be contained in interstellar clouds, illuminating the clouds.<ref>http://adsabs.harvard.edu/abs/1962ApJ...136.1135J</ref> At current count, there are over 1,100 known open clusters in the [[Milky Way]] alone, although this may be only a small percentage of the total.<ref name="am">http://www.maa.clell.de/Messier/open.html</ref>

The clusters themselves range from large conglomerates of thousands of stars to sparse clusters of only a dozen or less. The core or center of these clusters are a few light years across with an average density of a star per 1.5 cubic light years, about 500 times as dense as our solar neighborhood.

==History of Observation==

Open clusters have been known since [[antiquity]], although before the [[telescope]] the individual stars could not be resolved and they appeared as dim patches of light. One exception to this is the most well-known open cluster, the [[Pleiades]], which was easily observable as a group of similar stars, another known cluster was the [[Hyades]], the closest open cluster to us at only 150 [[light year|light years]].

Although there are various recording of the related stars of open clusters as far back as [[Ptolemy]] in 138 A.D, it wasn't until 1767 that the stars were recognized as such when [[Reverend]] [[John Michell]] first postulated that the stars of an open clusters had to be related because the chance of finding even one such cluster if they just happen to be a collection of unrelated stars were too astronomical.<ref name="am">http://www.maa.clell.de/Messier/open.html</ref> It wasn't until 1869 that the relation of stars in an open cluster was conclusively shown. That year Richard Proctor in his study of the Pleiades and the [[Ursa Major|Ursa Major Moving Cluster]], demonstrated using spectroscopy that the stars of the clusters have the same [[radial velocity]], indicating they are bound to each other by gravity. Proctor also showed that the stars of such clusters were all about the same distance from the [[Earth]], further showing they were moving together and were related.<ref>http://adsabs.harvard.edu/cgi-bin/bib_query?1869RSPS...18..169P</ref>

==Classification==

In 1930, R.J Trumpler introduced a classification system for open clusters based on three attributes. The first attribute is according to how concentrated the cluster is towards it's center, ranging from I-IV:

*I - Detached from the surrounding stars with strong concentration towards the cluster center
*II - Detached from the surrounding stars with weak concentration towards the cluster center
*III - Detached from the surrounding stars with no concentration towards the cluster center
*IV - Not well detached from surrounding stars

The second attribute is the range in luminosity or brightness of the member stars of the cluster, ranging from 1 to 3:

*1 - Small range in brightness in the stars of the cluster
*2 - Medium range in brightness in the stars of the cluster
*3 - Large range in brightness in the stars of the cluster

The third attribute is based on the number of stars in the cluster, referred to its ''richness'':

*p - Cluster has less then 5 stars, thus poor
*m - Cluster has between 50 and 100 stars, moderately rich
*r - Cluster has over 100 stars, rich

If the cluster lies within a [[nebula|nebulous structure]] it's classification is appended with an 'n'. Under this classification method for example, the Pleiades is classified as '''I3rn''' (Strong concentration towards the center, richly populated with stars that have a wide range in brightness, with nebulous material present). <ref>http://adsabs.harvard.edu/cgi-bin/bib_query?1930LicOB.420..154T</ref>

==Old Universe View==

Those who believe the Universe is millions or billions of years old often also believe that open clusters are initially formed when a large molecular cloud collapses due to nearby gravitational interactions or [[supernova]]. They believe that as the cloud collapses, it will fragment into increasingly smaller parts; they think that some of these fragments of gas and material that eventually result [[stellar evolution|in the creation of new stars]]. Eventually, according to these theories, the hottest and most massive of these stars drive away the remaining gasses through their stellar winds and radiation and star formation ceases.<ref>http://adsabs.harvard.edu/abs/1991MNRAS.249...76B</ref>

As an open cluster drifts through space, they believe, the individual stars of the loosely bound cluster slowly begin to drift away due to gravitational interactions with the rest of the galaxy. They believe that after few hundred million years the cluster would lose most of the member stars as individual stars orbiting the core of a [[galaxy]], connected only by their similar orbits in a disassociated group.<ref>http://adsabs.harvard.edu/abs/1998PASP..110.1117D</ref>

[[Category:Astronomy]]

==References==
{{reflist}}

User talk:BMcP

2010-02-07T00:19:07Z

BMcP: /* Old Earth / Young Earth */

{{Welcome}}[[User:AddisonDM|AddisonDM]] 18:28, 17 June 2009 (EDT)

== Images ==

Some are ready. --[[User:Joaquín Martínez|Joaquín Martínez]] 10:20, 24 June 2009 (EDT)

:: It seems that thumb does not work fine with .png images. See. [[Proxima Centauri]]. --[[User:Joaquín Martínez|Joaquín Martínez]] 11:00, 24 June 2009 (EDT)

::: It seems to work as a thumbnail if you add a specific pixel width to the parameters, figured this out when I was playing with the Alpha Centauri ones. It may be an issue with the wiki software and PNG thumbnails where it requires this, not sure, but adding the pixel width seems to solve it. --[[User:BMcP|BMcP]] 12;15, 24 June 2009 (EDT)

== VW / VY Canis Majoris ==
In your recent article, [[VW Canis Majoris]], why do you have "'''VY Canis Majoris''' is a..." and other mentions of a "VY Canis Majoris". This is very confusing. Is "VY" an alternate name to "VW"? --[[User:ChrisZ|ChrisZ]] 18:18, 27 July 2009 (EDT)
:No, it should be VY Canis Majoris, and it has been renamed so, I just made a mistake with the article title, is fixed now. --[[User:BMcP|BMcP]] 21:51, 27 July 2009 (EDT)

::: Zeta Puppis & VY Canis Majoris - Images; DONE. --[[User:Joaquín Martínez|Joaquín Martínez]] 22:53, 27 July 2009 (EDT)

==Image requests==
Your images have been uploaded [http://www.conservapedia.com/Special:Log/upload]. [[User:Karajou|Karajou]] 16:30, 29 October 2009 (EDT)

:And more: [[File:Hs-2005-26-c-large web.jpg|200px]][[File:Hs-1993-18-a-large web.jpg|200px]] [[User:Karajou|Karajou]] 16:17, 1 December 2009 (EST)

::Thanks Karajou! --[[User:BMcP|BMcP]] 16:18, 1 December 2009 (EST)

::And this one: [[File:B01Magellanic Clouds.jpg|200px]] :) [[User:Karajou|Karajou]] 16:25, 1 December 2009 (EST)

==Template==
Try this infobox template ([[Template:Night Sky]]) for your astronomy pages. [[User:Karajou|Karajou]] 17:18, 1 December 2009 (EST)

:Nice template, I will have to start incorporating that into my past (and future) articles. Of course it may mean I'll request several more pics. ;) --[[User:BMcP|BMcP]] 18:59, 1 December 2009 (EST)

::With the template, you have something like this: [[Andromeda galaxy]]. [[User:Karajou|Karajou]] 14:14, 2 December 2009 (EST)

[http://www.conservapedia.com/index.php?title=Antares&curid=92467&diff=733465&oldid=733457&rcid=805439 Nice usage of template] --[[User:Ed Poor|Ed Poor]] [[User talk:Ed Poor|Talk]] 13:13, 16 December 2009 (EST)

:Thanks! --[[User:BMcP|BMcP]] 08:47, 17 December 2009 (EST)

== More Images ==

[http://www.conservapedia.com/Conservapedia:Image_upload_requests#Constellation_Images Your image requests from today have been uploaded.] --[[User:TK|'''ṬK''']]/Admin[[User_Talk:TK|/Talk]] 14:09, 2 December 2009 (EST)

Found a smaller version of the Draco map, and inserted it into the article. I'll let you do the rest :) [[User:Karajou|Karajou]] 15:33, 2 December 2009 (EST)

==Additional templates==
The Night Sky template probably will not work for Draco, nor will it work for other constellations or stars. I'll work on adding both later on today. [[User:Karajou|Karajou]] 15:41, 2 December 2009 (EST)

:Yeah, although I am able to fill in some information, a more specialized template would be needed for constellations, given their special nature. Perhaps categories such as "abbreviation", "brightest star", "nearest star" and "main stars", that last one would be for the numerable amount of main stars. Main stars are those that actually are used in the outline of the constellation itself. --[[User:BMcP|BMcP]] 15:45, 2 December 2009 (EST)
::One is done, and placed within the Draco article; double-check for accuracy, and any suggestions that could be made within the templates. [[User:Karajou|Karajou]] 16:01, 2 December 2009 (EST)
:::The only thing I can think of off hand to add to the template is brightest star, otherwise it looks good. Also when done, if you can link me to the empty template, that would be cool. --[[User:BMcP|BMcP]] 16:09, 2 December 2009 (EST)
::::[[Template:Constellation]] Done. [[User:Karajou|Karajou]] 16:20, 2 December 2009 (EST)
:::::Very nice, it will certainly help when it comes to writing the individual constellation articles(88 total, that is a lot!). --[[User:BMcP|BMcP]] 16:23, 2 December 2009 (EST)

==Microsoft WorldWide Telescope==
This image [[File:RigelLocation.JPG|200px]] was done using Microsoft's program, and cropping it via Windows Paint. The idea is to have star maps which are not posted on Wikipedia. Any thoughts? [[User:Karajou|Karajou]] 12:11, 3 December 2009 (EST)

:Well I have no personal issue using the same images as Wikipedia, since usually it is a great resource of public domain and licensed to freely distribute images, that being said I totally am fine with creating our own. My only problem in that area is I have no upload rights so I turn to where I can.

:As for that specific image, I would also want the name of the constellation to appear as well as the other nearby stars (if possible), but have some sort of focus on the particular star (or deep sky object) that is the topic of the article, either through a circle or an arrow, etc. I don't know if that actual program can do that, but I know it is easy enough for me in Photoshop (which is what I use to manipulate images in). --[[User:BMcP|BMcP]] 12:49, 3 December 2009 (EST)

How's this version? [[File:RigelLocation.jpg|200px]] Higlighted star for the article; remainder in subdued fonts, with name of constellation in caps. [[User:Karajou|Karajou]] 13:07, 3 December 2009 (EST)

:That definitely looks better and in line with what I was suggesting. I may make the font for the others a little brightest (you can also use their bayer designation letter or number instead of full name for the other stars, while retaining the full name for the star in focus). What program are you using and how do you like it? I have thought on Winstar 2, curious how that looks. I have Stellarium, which is an excellent program for use in observations but not sure how well it is in making maps. --[[User:BMcP|BMcP]] 13:23, 3 December 2009 (EST)
::I have the Microsoft WorldWide Telescope [http://www.freewarefiles.com/Microsoft-WorldWide-Telescope_program_41720.html], which has a combination of photos and vector graphics. For making the star maps that are needed here, all that matters is to hit the "print screen" key on the keyboard, paste it within Microsoft Paint or PhotoShop, and adjust accordingly [[User:Karajou|Karajou]] 15:47, 3 December 2009 (EST)
::: Cool, well I am sure one of the programs will be good for me. However I will need a way to upload, as I am not allowed to. Also, on a related subject, could you approve the Milky Way pictures in the upload request page? Thanks. --[[User:BMcP|BMcP]] 18:58, 3 December 2009 (EST)

Sorry for forgetting these: [[File:MilkyWay1.jpg|200px]][[File:MilkyWaySpitzer.jpg|200px]] [[User:Karajou|Karajou]] 14:09, 16 December 2009 (EST)

:Thanks for uploading them :) --[[User:BMcP|BMcP]] 08:48, 17 December 2009 (EST)

== Image Uploads ==

I notice that you've almost always got a ton of image requests up - I've just gotten upload rights, so please, in the future, whenever you have a request, add it to my talk page as well as to our image upload request page, and I'll try and get on it immediately.

On an unrelated note, BMcP, I know we have had our differences on some issues, but I want to say that you've been a godsend to Conservapedia's astronomy articles. I look forward to more of your work! [[User:JacobB|JacobB]] 02:42, 27 December 2009 (EST)

== Nova ==

I'd turn Nova into a disambiguation page, then move the tv series to [[NOVA (tv series)]] and the astronomical phenomenon to [[Nova (star)]]. [[User:Geo.plrd|Geoff Plourde]][[User_talk:Geo.plrd|Complain!]] 13:29, 28 December 2009 (EST)

:I am not sure if I have the rights to do that, I am reasonably certain I do not have the rights to move the Nova TV page from "Nova" to "NOVA (tv series)". If I am wrong on that, please let me know. --[[User:BMcP|BMcP]] 13:44, 28 December 2009 (EST)

:Oh wait, it dawned on me. Rewrite the [[Nova]] page to be the disambiguation and create a new [[NOVA (tv series)]] and [[Nova (star)]] page. Okay, yes I understand now, thanks. --[[User:BMcP|BMcP]] 14:02, 28 December 2009 (EST)

== images ==

[http://www.conservapedia.com/File:Ia_Supernova.jpg][http://www.conservapedia.com/File:IsolatedNeutronStar.jpg][http://www.conservapedia.com/File:NeutronStar.jpg][http://www.conservapedia.com/File:0211_diameter_ill.jpg][http://www.conservapedia.com/File:Aquilae_illustration.jpg][http://www.conservapedia.com/File:PIA09221.jpg][http://www.conservapedia.com/File:Sn94d_hiz_big.jpg] [[User:JacobB|JacobB]] 16:07, 31 December 2009 (EST)
:[http://www.conservapedia.com/File:Evolved_star_fusion_shells.png] [[User:JacobB|JacobB]] 16:10, 31 December 2009 (EST)

:Thanks! --[[User:BMcP|BMcP]] 18:54, 2 January 2010 (EST)

== Repetition claim of time and location ==

The repetition claim that, for example, "the nebula is located around 6,500 light years away in the constellation of Taurus" would benefit from an explanation of the assumptions underlying the statement.--[[User:Aschlafly|Andy Schlafly]] 16:06, 5 January 2010 (EST)

: You never answered this question about your claims. I'm honestly curious what your assumptions are underlying your edits.--[[User:Aschlafly|Andy Schlafly]] 23:28, 16 January 2010 (EST)

::What is the issue? That it is 6,500 ± 1,600 light years or that it is in Taurus? --[[User:BMcP|BMcP]] 11:53, 17 January 2010 (EST)

:::Well, first of all I don't recall seeing the "± 1,600" part in your edit. Second of all, what are your assumptions underlying that claim? How is that claim made, what observation and assumptions is it based on?--[[User:Aschlafly|Andy Schlafly]] 13:50, 20 January 2010 (EST)

::::It is in the Astrometry section under distance of the Night Sky Template in the article. Distances of the nebula was done by using spectroscopy, which determines expansion velocity and comparing this with the nebula's angular expansion over time (using images over years[http://apod.nasa.gov/apod/ap011227.html]), using these we can calculate (within a margin) it's distance. The most precise measurement is around 6,300 light years, if you want, read the long technical explanation here.[http://adsabs.harvard.edu/abs/1973PASP...85..579T]. --[[User:BMcP|BMcP]] 14:03, 20 January 2010 (EST)

:::::BMcP, I'm asking a simple question and am hoping for a straightforward answer in your own words. If you don't know the answer, hopefully you're willing to look at it now with an open mind. Your explanation above doesn't state the assumptions. What are the assumptions?--[[User:Aschlafly|Andy Schlafly]] 14:15, 20 January 2010 (EST)

::::::I don't understand why you have any issue with this one astronomical object's distance. It isn't remarkable in that manner, many supernova remnants are much farther away. The only assumption I am making is those who are writing the original science, peer reviewed papers are not purposely fudging the data (and managed to trick those who reviewed the papers). However if I suspected that, I can conduct similar tests and see if I can duplicate their findings, or discover errors within them. --[[User:BMcP|BMcP]] 14:38, 20 January 2010 (EST)

:::::::I read the beginning of [http://adsabs.harvard.edu/abs/1973PASP...85..579T] with great interest. Unfortunately, though it says, "The dynamical methods all depend on the fact that we can measure both proper motions, in arc seconds year-1, and radial velocities, in km sec-1," it doesn't go into detail on how we can do that. The arc seconds/year, of course, can just be observed - but how do we measure the radial velocities? (I think your answer would make a great addition to some astronomy article!) --[[User:EvanW|EvanW]] 14:51, 20 January 2010 (EST)

(Unindented reply) Hello EvanW, I went and checked and we do not have a radial velocity page on this site. I will definitely have to put creating that page on my "to do" list since it is an important concept in astronomy. To answer your question though, in short, radial velocity speed at which an object is moving away from or toward an observer along the line of sight. We calculate this by observing displacement of spectral lines from their normal position in the observed object's spectra. Blueshifted if the object is moving towards us, redshifted if its moving away. The larger the blueshift or redshift, the larger the radial velocity. I hope that helps. --[[User:BMcP|BMcP]] 15:17, 20 January 2010 (EST)

:BMcP, on this site when someone states something as true, he should be able to explain ''why'' he thinks it is true. It's not enough to say the equivalent of "my assumptions are the same as that of liberals and atheists and I don't even know what those assumptions are." If you have no idea what the basis for a claim is (other than the equivalent of "liberals say so"), then please find out first, reconsider it with an open mind, and only then consider posting it.--[[User:Aschlafly|Andy Schlafly]] 16:41, 2 February 2010 (EST)

== images uploaded ==

[[Conservapedia:Image upload requests#Astronomy Images|your images, sir]] [[User:JacobB|JacobB]] 17:56, 9 January 2010 (EST)

== Old Earth / Young Earth ==

Do you have a gmail address we can chat on? There are some things I'd like to discuss with you. [[User:JacobB|JacobB]] 14:05, 3 February 2010 (EST)

:I am afraid I do not have gmail, I have AIM, ICQ, Skype, and Facebook for live communication. --[[User:BMcP|BMcP]] 16:09, 3 February 2010 (EST)
::Until we can discuss matters live, I would appreciate it if you could segregate any content which refers to the age or formation of astronomical phenomenon into sections which are clearly labeled at "old-earth views" or something like that, if you dispute the term evolutionist. I have tried to compromise with you by recognizing your views [http://www.conservapedia.com/index.php?title=Metallicity&diff=prev&oldid=751447][http://www.conservapedia.com/index.php?title=Globular_cluster&diff=prev&oldid=751446], but you seem determined to present your beliefs as fact. [http://www.conservapedia.com/index.php?title=Metallicity&diff=next&oldid=751447][http://www.conservapedia.com/index.php?title=Globular_cluster&diff=next&oldid=751446]. [[User:JacobB|JacobB]] 16:16, 3 February 2010 (EST)

:::Then use one of those, BMcP and Jacob. Not all compromises can be worked out easily in public, due to the human trait of posturing. Communication is important, and to arrive at compromise, even email would work. --<big>[[User:TK|'''ṬK''']]</big>/Admin[[User_Talk:TK|/Talk]] 16:59, 3 February 2010 (EST)
I've made further compromise edits to [[open cluster]]. Please email me, BMcP, if the current compromise edits on [[metallicity|these]] [[globular cluster|three]] [[open cluster|articles]] are not to your liking. If you are fine with them, but wish to change "evolutionist beliefs" to some other phrase, that's fine, just nothing that implies these beliefs are more valid, more mainstream, or more supported by evidence than a Biblical literalist understanding. [[User:JacobB|JacobB]] 16:19, 5 February 2010 (EST)

:They are not. You have none of the chat programs I mentioned? --[[User:BMcP|BMcP]] 14:42, 6 February 2010 (EST)

::Perhaps, BMcP, if you responded to Jacob's email, that would be a good beginning? Do I really need to be making such rudimentary suggestions to enable two people to converse? --<big>[[User:TK|'''ṬK''']]</big>/Admin[[User_Talk:TK|/Talk]] 15:05, 6 February 2010 (EST)

::I have received an email this evening, from it you sound like you sent previous one, but it did not get through? It looks to be working now, I will respond to it. --[[User:BMcP|BMcP]] 19:19, 6 February 2010 (EST)

==More templates==
I've created these templates ([[Template:Astronomy navbox]][[Template:Exo-Planets]][[Template:Stars]]) for use in various astronomy articles; I'm leaving them open for you to add to them or correct as you see fit. [[User:Karajou|Karajou]] 00:59, 4 February 2010 (EST)

User talk:BMcP

2010-02-06T19:42:24Z

BMcP: /* Old Earth / Young Earth */

{{Welcome}}[[User:AddisonDM|AddisonDM]] 18:28, 17 June 2009 (EDT)

== Images ==

Some are ready. --[[User:Joaquín Martínez|Joaquín Martínez]] 10:20, 24 June 2009 (EDT)

:: It seems that thumb does not work fine with .png images. See. [[Proxima Centauri]]. --[[User:Joaquín Martínez|Joaquín Martínez]] 11:00, 24 June 2009 (EDT)

::: It seems to work as a thumbnail if you add a specific pixel width to the parameters, figured this out when I was playing with the Alpha Centauri ones. It may be an issue with the wiki software and PNG thumbnails where it requires this, not sure, but adding the pixel width seems to solve it. --[[User:BMcP|BMcP]] 12;15, 24 June 2009 (EDT)

== VW / VY Canis Majoris ==
In your recent article, [[VW Canis Majoris]], why do you have "'''VY Canis Majoris''' is a..." and other mentions of a "VY Canis Majoris". This is very confusing. Is "VY" an alternate name to "VW"? --[[User:ChrisZ|ChrisZ]] 18:18, 27 July 2009 (EDT)
:No, it should be VY Canis Majoris, and it has been renamed so, I just made a mistake with the article title, is fixed now. --[[User:BMcP|BMcP]] 21:51, 27 July 2009 (EDT)

::: Zeta Puppis & VY Canis Majoris - Images; DONE. --[[User:Joaquín Martínez|Joaquín Martínez]] 22:53, 27 July 2009 (EDT)

==Image requests==
Your images have been uploaded [http://www.conservapedia.com/Special:Log/upload]. [[User:Karajou|Karajou]] 16:30, 29 October 2009 (EDT)

:And more: [[File:Hs-2005-26-c-large web.jpg|200px]][[File:Hs-1993-18-a-large web.jpg|200px]] [[User:Karajou|Karajou]] 16:17, 1 December 2009 (EST)

::Thanks Karajou! --[[User:BMcP|BMcP]] 16:18, 1 December 2009 (EST)

::And this one: [[File:B01Magellanic Clouds.jpg|200px]] :) [[User:Karajou|Karajou]] 16:25, 1 December 2009 (EST)

==Template==
Try this infobox template ([[Template:Night Sky]]) for your astronomy pages. [[User:Karajou|Karajou]] 17:18, 1 December 2009 (EST)

:Nice template, I will have to start incorporating that into my past (and future) articles. Of course it may mean I'll request several more pics. ;) --[[User:BMcP|BMcP]] 18:59, 1 December 2009 (EST)

::With the template, you have something like this: [[Andromeda galaxy]]. [[User:Karajou|Karajou]] 14:14, 2 December 2009 (EST)

[http://www.conservapedia.com/index.php?title=Antares&curid=92467&diff=733465&oldid=733457&rcid=805439 Nice usage of template] --[[User:Ed Poor|Ed Poor]] [[User talk:Ed Poor|Talk]] 13:13, 16 December 2009 (EST)

:Thanks! --[[User:BMcP|BMcP]] 08:47, 17 December 2009 (EST)

== More Images ==

[http://www.conservapedia.com/Conservapedia:Image_upload_requests#Constellation_Images Your image requests from today have been uploaded.] --[[User:TK|'''ṬK''']]/Admin[[User_Talk:TK|/Talk]] 14:09, 2 December 2009 (EST)

Found a smaller version of the Draco map, and inserted it into the article. I'll let you do the rest :) [[User:Karajou|Karajou]] 15:33, 2 December 2009 (EST)

==Additional templates==
The Night Sky template probably will not work for Draco, nor will it work for other constellations or stars. I'll work on adding both later on today. [[User:Karajou|Karajou]] 15:41, 2 December 2009 (EST)

:Yeah, although I am able to fill in some information, a more specialized template would be needed for constellations, given their special nature. Perhaps categories such as "abbreviation", "brightest star", "nearest star" and "main stars", that last one would be for the numerable amount of main stars. Main stars are those that actually are used in the outline of the constellation itself. --[[User:BMcP|BMcP]] 15:45, 2 December 2009 (EST)
::One is done, and placed within the Draco article; double-check for accuracy, and any suggestions that could be made within the templates. [[User:Karajou|Karajou]] 16:01, 2 December 2009 (EST)
:::The only thing I can think of off hand to add to the template is brightest star, otherwise it looks good. Also when done, if you can link me to the empty template, that would be cool. --[[User:BMcP|BMcP]] 16:09, 2 December 2009 (EST)
::::[[Template:Constellation]] Done. [[User:Karajou|Karajou]] 16:20, 2 December 2009 (EST)
:::::Very nice, it will certainly help when it comes to writing the individual constellation articles(88 total, that is a lot!). --[[User:BMcP|BMcP]] 16:23, 2 December 2009 (EST)

==Microsoft WorldWide Telescope==
This image [[File:RigelLocation.JPG|200px]] was done using Microsoft's program, and cropping it via Windows Paint. The idea is to have star maps which are not posted on Wikipedia. Any thoughts? [[User:Karajou|Karajou]] 12:11, 3 December 2009 (EST)

:Well I have no personal issue using the same images as Wikipedia, since usually it is a great resource of public domain and licensed to freely distribute images, that being said I totally am fine with creating our own. My only problem in that area is I have no upload rights so I turn to where I can.

:As for that specific image, I would also want the name of the constellation to appear as well as the other nearby stars (if possible), but have some sort of focus on the particular star (or deep sky object) that is the topic of the article, either through a circle or an arrow, etc. I don't know if that actual program can do that, but I know it is easy enough for me in Photoshop (which is what I use to manipulate images in). --[[User:BMcP|BMcP]] 12:49, 3 December 2009 (EST)

How's this version? [[File:RigelLocation.jpg|200px]] Higlighted star for the article; remainder in subdued fonts, with name of constellation in caps. [[User:Karajou|Karajou]] 13:07, 3 December 2009 (EST)

:That definitely looks better and in line with what I was suggesting. I may make the font for the others a little brightest (you can also use their bayer designation letter or number instead of full name for the other stars, while retaining the full name for the star in focus). What program are you using and how do you like it? I have thought on Winstar 2, curious how that looks. I have Stellarium, which is an excellent program for use in observations but not sure how well it is in making maps. --[[User:BMcP|BMcP]] 13:23, 3 December 2009 (EST)
::I have the Microsoft WorldWide Telescope [http://www.freewarefiles.com/Microsoft-WorldWide-Telescope_program_41720.html], which has a combination of photos and vector graphics. For making the star maps that are needed here, all that matters is to hit the "print screen" key on the keyboard, paste it within Microsoft Paint or PhotoShop, and adjust accordingly [[User:Karajou|Karajou]] 15:47, 3 December 2009 (EST)
::: Cool, well I am sure one of the programs will be good for me. However I will need a way to upload, as I am not allowed to. Also, on a related subject, could you approve the Milky Way pictures in the upload request page? Thanks. --[[User:BMcP|BMcP]] 18:58, 3 December 2009 (EST)

Sorry for forgetting these: [[File:MilkyWay1.jpg|200px]][[File:MilkyWaySpitzer.jpg|200px]] [[User:Karajou|Karajou]] 14:09, 16 December 2009 (EST)

:Thanks for uploading them :) --[[User:BMcP|BMcP]] 08:48, 17 December 2009 (EST)

== Image Uploads ==

I notice that you've almost always got a ton of image requests up - I've just gotten upload rights, so please, in the future, whenever you have a request, add it to my talk page as well as to our image upload request page, and I'll try and get on it immediately.

On an unrelated note, BMcP, I know we have had our differences on some issues, but I want to say that you've been a godsend to Conservapedia's astronomy articles. I look forward to more of your work! [[User:JacobB|JacobB]] 02:42, 27 December 2009 (EST)

== Nova ==

I'd turn Nova into a disambiguation page, then move the tv series to [[NOVA (tv series)]] and the astronomical phenomenon to [[Nova (star)]]. [[User:Geo.plrd|Geoff Plourde]][[User_talk:Geo.plrd|Complain!]] 13:29, 28 December 2009 (EST)

:I am not sure if I have the rights to do that, I am reasonably certain I do not have the rights to move the Nova TV page from "Nova" to "NOVA (tv series)". If I am wrong on that, please let me know. --[[User:BMcP|BMcP]] 13:44, 28 December 2009 (EST)

:Oh wait, it dawned on me. Rewrite the [[Nova]] page to be the disambiguation and create a new [[NOVA (tv series)]] and [[Nova (star)]] page. Okay, yes I understand now, thanks. --[[User:BMcP|BMcP]] 14:02, 28 December 2009 (EST)

== images ==

[http://www.conservapedia.com/File:Ia_Supernova.jpg][http://www.conservapedia.com/File:IsolatedNeutronStar.jpg][http://www.conservapedia.com/File:NeutronStar.jpg][http://www.conservapedia.com/File:0211_diameter_ill.jpg][http://www.conservapedia.com/File:Aquilae_illustration.jpg][http://www.conservapedia.com/File:PIA09221.jpg][http://www.conservapedia.com/File:Sn94d_hiz_big.jpg] [[User:JacobB|JacobB]] 16:07, 31 December 2009 (EST)
:[http://www.conservapedia.com/File:Evolved_star_fusion_shells.png] [[User:JacobB|JacobB]] 16:10, 31 December 2009 (EST)

:Thanks! --[[User:BMcP|BMcP]] 18:54, 2 January 2010 (EST)

== Repetition claim of time and location ==

The repetition claim that, for example, "the nebula is located around 6,500 light years away in the constellation of Taurus" would benefit from an explanation of the assumptions underlying the statement.--[[User:Aschlafly|Andy Schlafly]] 16:06, 5 January 2010 (EST)

: You never answered this question about your claims. I'm honestly curious what your assumptions are underlying your edits.--[[User:Aschlafly|Andy Schlafly]] 23:28, 16 January 2010 (EST)

::What is the issue? That it is 6,500 ± 1,600 light years or that it is in Taurus? --[[User:BMcP|BMcP]] 11:53, 17 January 2010 (EST)

:::Well, first of all I don't recall seeing the "± 1,600" part in your edit. Second of all, what are your assumptions underlying that claim? How is that claim made, what observation and assumptions is it based on?--[[User:Aschlafly|Andy Schlafly]] 13:50, 20 January 2010 (EST)

::::It is in the Astrometry section under distance of the Night Sky Template in the article. Distances of the nebula was done by using spectroscopy, which determines expansion velocity and comparing this with the nebula's angular expansion over time (using images over years[http://apod.nasa.gov/apod/ap011227.html]), using these we can calculate (within a margin) it's distance. The most precise measurement is around 6,300 light years, if you want, read the long technical explanation here.[http://adsabs.harvard.edu/abs/1973PASP...85..579T]. --[[User:BMcP|BMcP]] 14:03, 20 January 2010 (EST)

:::::BMcP, I'm asking a simple question and am hoping for a straightforward answer in your own words. If you don't know the answer, hopefully you're willing to look at it now with an open mind. Your explanation above doesn't state the assumptions. What are the assumptions?--[[User:Aschlafly|Andy Schlafly]] 14:15, 20 January 2010 (EST)

::::::I don't understand why you have any issue with this one astronomical object's distance. It isn't remarkable in that manner, many supernova remnants are much farther away. The only assumption I am making is those who are writing the original science, peer reviewed papers are not purposely fudging the data (and managed to trick those who reviewed the papers). However if I suspected that, I can conduct similar tests and see if I can duplicate their findings, or discover errors within them. --[[User:BMcP|BMcP]] 14:38, 20 January 2010 (EST)

:::::::I read the beginning of [http://adsabs.harvard.edu/abs/1973PASP...85..579T] with great interest. Unfortunately, though it says, "The dynamical methods all depend on the fact that we can measure both proper motions, in arc seconds year-1, and radial velocities, in km sec-1," it doesn't go into detail on how we can do that. The arc seconds/year, of course, can just be observed - but how do we measure the radial velocities? (I think your answer would make a great addition to some astronomy article!) --[[User:EvanW|EvanW]] 14:51, 20 January 2010 (EST)

(Unindented reply) Hello EvanW, I went and checked and we do not have a radial velocity page on this site. I will definitely have to put creating that page on my "to do" list since it is an important concept in astronomy. To answer your question though, in short, radial velocity speed at which an object is moving away from or toward an observer along the line of sight. We calculate this by observing displacement of spectral lines from their normal position in the observed object's spectra. Blueshifted if the object is moving towards us, redshifted if its moving away. The larger the blueshift or redshift, the larger the radial velocity. I hope that helps. --[[User:BMcP|BMcP]] 15:17, 20 January 2010 (EST)

:BMcP, on this site when someone states something as true, he should be able to explain ''why'' he thinks it is true. It's not enough to say the equivalent of "my assumptions are the same as that of liberals and atheists and I don't even know what those assumptions are." If you have no idea what the basis for a claim is (other than the equivalent of "liberals say so"), then please find out first, reconsider it with an open mind, and only then consider posting it.--[[User:Aschlafly|Andy Schlafly]] 16:41, 2 February 2010 (EST)

== images uploaded ==

[[Conservapedia:Image upload requests#Astronomy Images|your images, sir]] [[User:JacobB|JacobB]] 17:56, 9 January 2010 (EST)

== Old Earth / Young Earth ==

Do you have a gmail address we can chat on? There are some things I'd like to discuss with you. [[User:JacobB|JacobB]] 14:05, 3 February 2010 (EST)

:I am afraid I do not have gmail, I have AIM, ICQ, Skype, and Facebook for live communication. --[[User:BMcP|BMcP]] 16:09, 3 February 2010 (EST)
::Until we can discuss matters live, I would appreciate it if you could segregate any content which refers to the age or formation of astronomical phenomenon into sections which are clearly labeled at "old-earth views" or something like that, if you dispute the term evolutionist. I have tried to compromise with you by recognizing your views [http://www.conservapedia.com/index.php?title=Metallicity&diff=prev&oldid=751447][http://www.conservapedia.com/index.php?title=Globular_cluster&diff=prev&oldid=751446], but you seem determined to present your beliefs as fact. [http://www.conservapedia.com/index.php?title=Metallicity&diff=next&oldid=751447][http://www.conservapedia.com/index.php?title=Globular_cluster&diff=next&oldid=751446]. [[User:JacobB|JacobB]] 16:16, 3 February 2010 (EST)

:::Then use one of those, BMcP and Jacob. Not all compromises can be worked out easily in public, due to the human trait of posturing. Communication is important, and to arrive at compromise, even email would work. --<big>[[User:TK|'''ṬK''']]</big>/Admin[[User_Talk:TK|/Talk]] 16:59, 3 February 2010 (EST)
I've made further compromise edits to [[open cluster]]. Please email me, BMcP, if the current compromise edits on [[metallicity|these]] [[globular cluster|three]] [[open cluster|articles]] are not to your liking. If you are fine with them, but wish to change "evolutionist beliefs" to some other phrase, that's fine, just nothing that implies these beliefs are more valid, more mainstream, or more supported by evidence than a Biblical literalist understanding. [[User:JacobB|JacobB]] 16:19, 5 February 2010 (EST)

:They are not. You have none of the chat programs I mentioned? --[[User:BMcP|BMcP]] 14:42, 6 February 2010 (EST)

==More templates==
I've created these templates ([[Template:Astronomy navbox]][[Template:Exo-Planets]][[Template:Stars]]) for use in various astronomy articles; I'm leaving them open for you to add to them or correct as you see fit. [[User:Karajou|Karajou]] 00:59, 4 February 2010 (EST)

User talk:BMcP

2010-02-03T21:09:30Z

BMcP: /* Old Earth / Young Earth */

Open cluster

2010-02-03T21:04:20Z

BMcP: Created page with '{{image request}} An '''open cluster''', sometimes referred to as an '''open star cluster''' or a '''galactic cluster''', is a group of physically related stars that hav...'

{{image request}}
An '''open cluster''', sometimes referred to as an '''open star cluster''' or a '''galactic cluster''', is a group of physically related [[star|stars]] that have similar chemical composition and age held together by mutual [[gravity]]. In contrast to a [[globular cluster|globular clusters]], the stars of an open cluster are only loosely gravitationally bound to each other. Open clusters have only been observed in galaxies with active star formation, such as [[spiral galaxy|spiral]] and [[irregular galaxy|irregular galaxies]], for spiral galaxies, they are found within the spiral arms.<ref>http://adsabs.harvard.edu/abs/1979stcl.book.....P</ref> These clusters are made up of [[metallicity|younger population I stars]] and can be traced back to [[molecular cloud|molecular clouds]] where they formed. The youngest clusters may still be contained in the clouds they birthed from, illuminating it.<ref>http://adsabs.harvard.edu/abs/1962ApJ...136.1135J</ref> At current count, there are over 1,100 known open clusters in the [[Milky Way]] alone, although this may be only a small percentage of the total.<ref name="am">http://www.maa.clell.de/Messier/open.html</ref>

The clusters themselves range from large conglomerates of thousands of stars to sparse clusters of only a dozen or less. The core or center of these clusters are a few light years across with an average density of a star per 1.5 cubic light years, about 500 times as dense as our solar neighborhood.

==History of Observation==

Open clusters have been known since [[antiquity]], although before the [[telescope]] the individual stars could not be resolved and they appeared as dim patches of light. One exception to this is the most well-known open cluster, the [[Pleiades]], which was easily observable as a group of similar stars, another known cluster was the [[Hyades]], the closest open cluster to us at only 150 [[light year|light years]].

Although there are various recording of the related stars of open clusters as far back as [[Ptolemy]] in 138 A.D, it wasn't until 1767 that the stars were recognized as such when [[Reverend]] [[John Michell]] first postulated that the stars of an open clusters had to be related because the chance of finding even one such cluster if they just happen to be a collection of unrelated stars were too astronomical.<ref name="am">http://www.maa.clell.de/Messier/open.html</ref> It wasn't until 1869 that the relation of stars in an open cluster was conclusively shown. That year Richard Proctor in his study of the Pleiades and the [[Ursa Major|Ursa Major Moving Cluster]], demonstrated using spectroscopy that the stars of the clusters have the same [[radical velocity]], indicating they are bound to each other by gravity. Proctor also showed that the stars of such clusters were all about the same distance from the [[Earth]], further showing they were moving together and were related.<ref>http://adsabs.harvard.edu/cgi-bin/bib_query?1869RSPS...18..169P</ref>

==Cluster Formation==

It is believed that open clusters are initially formed when a large molecular cloud collapses due to nearby gravitational interactions or [[supernova]]. As the cloud collapses, it will fragment into increasingly smaller parts, it is some of these fragments of gas and material that eventually result [[stellar evolution|in the creation of new stars]]. Eventually the hottest and most massive of these stars drive away the remaining gasses through their stellar winds and radiation and star formation ceases.<ref>http://adsabs.harvard.edu/abs/1991MNRAS.249...76B</ref>

Over time as an open cluster drifts through space, the individual stars of the loosely bound cluster slowly begin to drift away due to gravitational interactions with the rest of the galaxy. It is estimated that after few hundred million years the cluster would lose most of the member stars as individual stars orbiting the core of a [[galaxy]], connected only by their similar orbits in a disassociated group.<ref>http://adsabs.harvard.edu/abs/1998PASP..110.1117D</ref>

==Classification==

In 1930, R.J Trumpler introduced a classification system for open clusters based on three attributes. The first attribute is according to how concentrated the cluster is towards it's center, ranging from I-IV:

*I - Detached from the surrounding stars with strong concentration towards the cluster center
*II - Detached from the surrounding stars with weak concentration towards the cluster center
*III - Detached from the surrounding stars with no concentration towards the cluster center
*IV - Not well detached from surrounding stars

The second attribute is the range in luminosity or brightness of the member stars of the cluster, ranging from 1 to 3:

*1 - Small range in brightness in the stars of the cluster
*2 - Medium range in brightness in the stars of the cluster
*3 - Large range in brightness in the stars of the cluster

The third attribute is based on the number of stars in the cluster, referred to its ''richness'':

*p - Cluster has less then 5 stars, thus poor
*m - Cluster has between 50 and 100 stars, moderately rich
*r - Cluster has over 100 stars, rich

If the cluster lies within a [[nebula|nebulous structure]] it's classification is appended with an 'n'. Under this classification method for example, the Pleiades is classified as '''I3rn''' (Strong concentration towards the center, richly populated with stars that have a wide range in brightness, with nebulous material present). <ref>http://adsabs.harvard.edu/cgi-bin/bib_query?1930LicOB.420..154T</ref>

[[Category:Astronomy]]

==References==
{{reflist}}

Talk:Metallicity

2010-02-03T15:58:46Z

BMcP:

Any statements which are not factual, but instead advances an agenda, ought to either be removed entirely or put in a seperate section labelled "Evolutionist Beliefs" or something. [[User:JacobB|JacobB]] 15:48, 2 February 2010 (EST)

:There is no attempt to advance an agenda other then to supply the best information found according to current theories in astrophysics on what metallicty is and how it may be used in measuring age. We don't do this for an agenda, we do this because we want to understand the universe which fascinates us so. If you want to add some sort of YEC section like was done for the Milky Way as a equable solution, I am fine with that. Just a FYI, evolutionist isn't an applicable word for work in astrophysics, we are dealing with ages and Deep Time far longer then those biologists use in calculating time scales for evolution. Also feel free to contact me on AIM. --[[User:BMcP|BMcP]] 10:58, 3 February 2010 (EST)

Metallicity

2010-02-03T15:52:15Z

BMcP:

'''Metallicity''' is a term in [[astronomy]] that refers to the proportion of elements in an astronomical object (usually a [[star]]) that are other than [[hydrogen]] or [[helium]]. In astronomy, all elements heavier then hydrogen and helium are collectively referred to with the blanket term "metals"<ref name="metal">https://edocs.uis.edu/jmart5/www/rrlyrae/metals.htm</ref>. Therefore a star or a [[nebula]] that contained significant amounts of elements such as [[carbon]], [[oxygen]], or [[nitrogen]] would be considered "metal rich" even though those same elements are classified as nonmetals in chemistry<ref>http://www.wisegeek.com/what-is-metallicity.htm</ref>.

Usually, metallicity is expressed in terms of the relative amounts of [[iron]] and hydrogen present in a star, since iron is among the easiest elements to measure with spectral data in the visible spectrum. This is determined by analyzing absorption lines in a stellar spectrum using a spectrometer, compared to the star's solar value. The ratio of the amount of iron to the amount of hydrogen in the object is divided by the ratio of the amount of iron to the amount of hydrogen in the Sun (which has a metallicity of 1.6 percent by mass). This value, expressed as [Fe/H], is calculated using the following logarithmic formula<ref name="metal">https://edocs.uis.edu/jmart5/www/rrlyrae/metals.htm</ref>.

<center><math> [\mathrm{Fe}/\mathrm{H}] = \log_{10}{\left(\frac{N_{\mathrm{Fe}}}{N_{\mathrm{H}}}\right)_{star}} - \log_{10}{\left(\frac{N_{\mathrm{Fe}}}{N_{\mathrm{H}}}\right)_{sun}} </math></center>

Where ''N''Fe and ''N''H is the number of iron and hydrogen atoms per unit of volume respectively. Using this formula, a star that has a higher metallicity then our [[Sun]] will have a positive logarithmic value, while any star with a lower metallicity then our sun will result in a negative value. Because the logarithm is based on powers of ten; a star with a value of [Fe/H] = -1 will have an abundance of heavy elements (metallicity) one tenth of that of our sun, while a value of [Fe/H] =+1 represents a star with ten times the abundance of heavy elements of our sun. Measurements of thousands of stars have resulted in a generally established range from -4 (extremely metal-poor) to +1 (very metal-rich).

==Types of stars according to Metallicity==

'''Population I stars''' are stars that are considered to be the most metal-rich (or highest metallicity), our sun falls into this category. Although such stars may be as metal-poor as >-1 in comparison to the sun, many have more metallicity then our own sun. Such stars tend to be found either in, or near the plane of a spiral galaxy such as our own [[Milky Way]]. Some of these stars are referred to as ''Extreme Population I stars'', a classification reserved for what are believed to be the youngest stars, and are always found in the spiral arms. Class O and B stars, T Tauri stars and other stars just entering the main sequence of stellar evolution are counted among these stars.<ref>http://www.daviddarling.info/encyclopedia/P/PopI.html</ref>.

'''Population II stars''' are metal-poor stars (negative values beyond -1), usually located in the bulge near to the center of spiral galaxies as well as the galactic halo. Such stars are also common in Globular Clusters and make up the overwhelming number of the stellar population in elliptical galaxies. These stars are considered to be older then Population I stars, and are the reasoned source of most of the elements in the periodic table<ref>http://www.daviddarling.info/encyclopedia/P/PopII.html</ref>.

'''Population III stars''' are essentially metal-free stars, although some have metals at the end of their lives. Population III stars were considered to be extremely massive and hot but have not been directly observed. According to the Big Bang theory, these are the first hypothetical stars to have formed in the universe. Indirect evidence of their existence has been found through looking at [[General theory of relativity|gravitationally lensed]]<ref>http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2002ApJ...567..532H</ref>, and distant faint blue galaxies in the very distant universe<ref>http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2003ApJ...596..797F</ref>.

==Metallicity as a measurement of star age==

The metallicity of such astronomical objects is one method astronomers use that may offer clues to those objects' ages. According to the [[Big Bang|Big Bang theory]], when the universe first formed, it consisted mostly of hydrogen with a sizable proportion of helium; only trace amounts of [[lithium]] and [[beryllium]] are believed to have been created, with no heavier elements forming. Based on this model, older stars will have lower metallicity than younger stars, as all other elements were created through Stellar and Supernova nucleosynthesis.

[[Category:Astronomy]]

==References==
{{reflist}}

Talk:Globular cluster

2010-02-03T15:30:58Z

BMcP:

== Editing ==
Conservapedia does not eschew points of view contrary to YEC, we merely ask for proof. Therefore the mere mention of an old earth is not subject to removal automatically. We strive for fairness here, offering the POV of those who believe in a Young Earth, which other, more gossipy on-line encyclopedia's will not. Doing that does not mean we wish to exclude other POV's. We offer information so the reader can make their own decision, given the facts available. --<big>[[User:TK|'''ṬK''']]</big>/Admin[[User_Talk:TK|/Talk]] 16:56, 2 February 2010 (EST)

:Thanks. I have no objections if someone wants to add a YEC POV to this article, although I am not aware of any YEC hypotheses regarding Globular Clusters. --[[User:BMcP|BMcP]] 10:30, 3 February 2010 (EST)

Globular cluster

2010-02-03T15:29:22Z

BMcP: "Evolutionist" is incorrect term here, as this deals with cosmology and astronomy. I have no objection if someone wants to add in a "YEC" theory and view, but the standard view shouldn't disregarded.

{{image request}}
A '''globular cluster''' is a spherical grouping of [[star|stars]] that share a common origin and orbits the galactic core of a [[galaxy]] as a satellite. They are very tightly bound by [[gravity]] and contain anywhere from tens of thousands to million of stars in an area that is only some 300 light years across or less, and are generally oblate spheroids in shape. The density of the clusters are on average around 0.4 stars per cubic [[parsec]], but increases toward to the center of the cluster, reaching as high as 100 or even a 1000 stars per cubic parsec.<ref>http://www.astro.keele.ac.uk/workx/globulars/globulars.html</ref>

Unlike [[open cluster|open clusters]], which contain [[metallicity|younger population I stars]] and reside in the [[galactic disk]], globular clusters are made up of older population II stars and are found in either the [[galactic bulge]] or [[galactic halo]]. Some globular clusters are found as far out as 131,000 light years from the core of the galaxy.<ref>http://adsabs.harvard.edu/abs/1996A&A...313..119D</ref> Current, there are 158 known globular clusters around the [[Milky Way]], with several more perhaps yet to be discovered, all moving in highly eccentric orbits.<ref>http://www.seds.org/~spider/spider/MWGC/mwgc.html</ref> Beyond the Milky Way, most other galaxies in the Local Group and beyond have globular clusters. [[Andromeda_galaxy|Andromeda]] is known to have some 500.

==History==

Abraham Ihle, an amateur [[astronomer]] from [[Germany]] was the first to discover a globular cluster when he found the cluster M22 in 1665, however at the time his telescope was not able to resolve the individual stars. [[Charles Messier]] was the first to identify globular clusters as being made up of individual stars when he observed the cluster M4. It was [[William Herschel]] though who first coined the term globular cluster in his catalog of deep sky objects in 1789. Herschel also discovered 37 such clusters alone, as well as fully resolve the stars in 33 previous discovered ones.

In 1918, [[Harlow Shapley]] used his studies of globular clusters and their asymmetrical distribution in the galaxy to calculate both the distance of the [[Sun]] to the galactic center, and the overall dimensions of the [[Milky Way]] itself. Although the measurements he made were off from the actual size of the galaxy, due to not taking into account dust in the Milky Way diminishing light from the various clusters, he did in fact show the galaxy was much larger then previously believed.<ref>http://adsabs.harvard.edu/abs/1918PASP...30...42S</ref>

==Composition==

The stars themselves that make up globular clusters are all metal-poor population II stars, older stars similar to those located in the central budge of the Milky Way. There is also no detectable gas or dust in these clusters suggesting that all such material had long ago been used up to create stars according to current star formation theories.

Globular clusters are further divided into two major groupings known as ''Oosterhoff groups'', the difference between the level of [[metallicity]] found in the stars in the cluster. Clusters of the type I group are found to have somewhat weak metal absorption line in their spectra, while Type II have very weak metal lines. As such, Type I clusters are referred to as "metal-rich" and Type II as "metal-poor". Both types are metal-poor in comparison to younger population I stars found in the [[galactic disk]].<ref>van Albada, T. S.; Baker, Norman (1973). "On the Two Oosterhoff Groups of Globular Clusters". Astrophysical Journal 185: 477–498. do:10.1086/152434.</ref> In the Milky Way, the more metal-poor type II clusters are located in the outer part of the galactic halo, while the more metal-rich clusters are found near the galactic budge.<ref>http://adsabs.harvard.edu/abs/1976AJ.....81.1095H</ref> Both types of globular cluster populations have been found in several galaxies, being most common in large [[elliptical galaxy|elliptical galaxies]]. What causes the difference between the two types of clusters is not exactly known. Some scenarios to explain this include galaxy mergers, the absorption of satellite galaxies, and staggered star formation within galaxies.<ref>http://adsabs.harvard.edu/abs/2002astro.ph..7607Y</ref>

==Current Theories on Formation and Age==

Globular clusters are generally believed to be around 9 to 13 billion years in age and initially form as a loose collection of stars. Current hypotheses suggest as the cluster passes into "adolescence", the stars near the center of the cluster begin to collapse in towards each other. This collapse ends when the interaction of [[binary star|binary systems]] prevent any further contraction, at this point the cluster is at "middle age". Eventually over time, stars in the binary systems are ejected by gravitational disruption as the cluster passes through "old age". It is believed that virtually all globular clusters are far along in the "old age" portion of their evolution. However a more recent study of 13 globular clusters suggests though that some of the clusters may actually be much younger then initially believed. This is due to the fact that three of the clusters were found to still have a large number of [[x-ray]] binaries, suggesting that not enough time has passed to eject many binary companions from the cluster. If these new observations are confirmed, this would challenge the current theories on the evolution of such clusters.<ref>http://www.astronomynow.com/Oldglobularclusterssurprisinglyyoung.html</ref>

[[Category: Astronomy]]

==References==
{{reflist}}

Talk:Animal

2010-02-02T20:54:46Z

BMcP: /* (extra section break inserted to help things out) */

Metallicity

2010-02-02T20:39:06Z

BMcP: At least discuss objections on the talk page before ripping out whole sections of resereached info

'''Metallicity''' is a term in [[astronomy]] that refers to the proportion of elements in an astronomical object (usually a [[star]]) that are other than [[hydrogen]] or [[helium]]. In astronomy, all elements heavier then hydrogen and helium are collectively referred to with the blanket term "metals"<ref name="metal">https://edocs.uis.edu/jmart5/www/rrlyrae/metals.htm</ref>. Therefore a star or a [[nebula]] that contained significant amounts of elements such as [[carbon]], [[oxygen]], or [[nitrogen]] would be considered "metal rich" even though those same elements are classified as nonmetals in chemistry<ref>http://www.wisegeek.com/what-is-metallicity.htm</ref>.

The metallicity of such astronomical objects may offer clues to those objects' ages. According to the [[Big Bang|Big Bang theory]], when the universe first formed, it consisted mostly of hydrogen with a sizable proportion of helium; only trace amounts of [[lithium]] and [[beryllium]] are believed to have been created, with no heavier elements forming. Therefore, older stars will have lower metallicity than younger stars, as all other elements were created through Stellar and Supernova nucleosynthesis.

Usually, metallicity is expressed in terms of the relative amounts of [[iron]] and hydrogen present in a star, since iron is among the easiest elements to measure with spectral data in the visible spectrum. This is determined by analyzing absorption lines in a stellar spectrum using a spectrometer, compared to the star's solar value. The ratio of the amount of iron to the amount of hydrogen in the object is divided by the ratio of the amount of iron to the amount of hydrogen in the Sun (which has a metallicity of 1.6 percent by mass). This value, expressed as [Fe/H], is calculated using the following logarithmic formula<ref name="metal">https://edocs.uis.edu/jmart5/www/rrlyrae/metals.htm</ref>.

<center><math> [\mathrm{Fe}/\mathrm{H}] = \log_{10}{\left(\frac{N_{\mathrm{Fe}}}{N_{\mathrm{H}}}\right)_{star}} - \log_{10}{\left(\frac{N_{\mathrm{Fe}}}{N_{\mathrm{H}}}\right)_{sun}} </math></center>

Where ''N''Fe and ''N''H is the number of iron and hydrogen atoms per unit of volume respectively. Using this formula, a star that has a higher metallicity then our [[Sun]] will have a positive logarithmic value, while any star with a lower metallicity then our sun will result in a negative value. Because the logarithm is based on powers of ten; a star with a value of [Fe/H] = -1 will have an abundance of heavy elements (metallicity) one tenth of that of our sun, while a value of [Fe/H] =+1 represents a star with ten times the abundance of heavy elements of our sun. Measurements of thousands of stars have resulted in a generally established range from -4 (extremely metal-poor) to +1 (very metal-rich).

==Types of stars according to Metallicity==

'''Population I stars''' are stars that are considered to be the most metal-rich (or highest metallicity), our sun falls into this category. Although such stars may be as metal-poor as >-1 in comparison to the sun, many have more metallicity then our own sun. Such stars tend to be found either in, or near the plane of a spiral galaxy such as our own [[Milky Way]]. Some of these stars are referred to as ''Extreme Population I stars'', or the youngest stars, found in the spiral arms, class O and B stars, T Tauri stars and other stars just entering the main sequence of stellar evolution are counted among these stars<ref>http://www.daviddarling.info/encyclopedia/P/PopI.html</ref>.

'''Population II stars''' are metal-poor stars (negative values beyond -1), usually located in the bulge near to the center of spiral galaxies as well as the galactic halo. Such stars are also common in Globular Clusters and make up the overwhelming number of the stellar population in elliptical galaxies. These stars are considered to be older then Population I stars, and are the reasoned source of most of the elements in the periodic table<ref>http://www.daviddarling.info/encyclopedia/P/PopII.html</ref>.

'''Population III stars''', sometimes referred to as metal-free stars (although having metals at the end of their lives), are the hypothetical first stars believed to have form after matter condensed out of the Big Bang in the early universe. Population III stars were considered to be extremely massive and hot but have not been directly observed. Indirect evidence of their existence has been found through looking at gravitationally lensed<ref>http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2002ApJ...567..532H</ref>, and distant faint blue galaxies in the very distant universe<ref>http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2003ApJ...596..797F</ref>.

[[Category:Astronomy]]

==References==
{{reflist}}

Globular cluster

2010-02-02T20:37:04Z

BMcP: At least talkon the talk page before ripping out whole sections of resereached info

{{image request}}
A '''globular cluster''' is a spherical grouping of [[star|stars]] that share a common origin and orbits the galactic core of a [[galaxy]] as a satellite. They are very tightly bound by [[gravity]] and contain anywhere from tens of thousands to million of stars in an area that is only some 300 light years across or less, and are generally oblate spheroids in shape. The density of the clusters are on average around 0.4 stars per cubic [[parsec]], but increases toward to the center of the cluster, reaching as high as 100 or even a 1000 stars per cubic parsec.<ref>http://www.astro.keele.ac.uk/workx/globulars/globulars.html</ref>

Unlike [[open cluster|open clusters]], which contain [[metallicity|younger population I stars]] and reside in the [[galactic disk]], globular clusters are made up of older population II stars and are found in either the [[galactic bulge]] or [[galactic halo]]. Some globular clusters are found as far out as 131,000 light years from the core of the galaxy.<ref>http://adsabs.harvard.edu/abs/1996A&A...313..119D</ref> Current, there are 158 known globular clusters around the [[Milky Way]], with several more perhaps yet to be discovered, all moving in highly eccentric orbits.<ref>http://www.seds.org/~spider/spider/MWGC/mwgc.html</ref> Beyond the Milky Way, most other galaxies in the Local Group and beyond have globular clusters. [[Andromeda_galaxy|Andromeda]] is known to have some 500.

==History==

Abraham Ihle, an amateur [[astronomer]] from [[Germany]] was the first to discover a globular cluster when he found the cluster M22 in 1665, however at the time his telescope was not able to resolve the individual stars. [[Charles Messier]] was the first to identify globular clusters as being made up of individual stars when he observed the cluster M4. It was [[William Herschel]] though who first coined the term globular cluster in his catalog of deep sky objects in 1789. Herschel also discovered 37 such clusters alone, as well as fully resolve the stars in 33 previous discovered ones.

In 1918, [[Harlow Shapley]] used his studies of globular clusters and their asymmetrical distribution in the galaxy to calculate both the distance of the [[Sun]] to the galactic center, and the overall dimensions of the [[Milky Way]] itself. Although the measurements he made were off from the actual size of the galaxy, due to not taking into account dust in the Milky Way diminishing light from the various clusters, he did in fact show the galaxy was much larger then previously believed.<ref>http://adsabs.harvard.edu/abs/1918PASP...30...42S</ref>

==Age and Composition==

The stars themselves that make up globular clusters are all metal-poor population II stars, older stars similar to those located in the central budge of the Milky Way. There is also no detectable gas or dust in these clusters suggesting that all such material had long ago been used up to create stars.

Globular clusters are further divided into two major groupings known as ''Oosterhoff groups'', the difference between the level of [[metallicity]] found in the stars in the cluster. Clusters of the type I group are found to have somewhat weak metal absorption line in their spectra, while Type II have very weak metal lines. As such, Type I clusters are referred to as "metal-rich" and Type II as "metal-poor". Both types are metal-poor in comparison to younger population I stars found in the [[galactic disk]].<ref>van Albada, T. S.; Baker, Norman (1973). "On the Two Oosterhoff Groups of Globular Clusters". Astrophysical Journal 185: 477–498. do:10.1086/152434.</ref> In the Milky Way, the more metal-poor type II clusters are located in the outer part of the galactic halo, while the more metal-rich clusters are found near the galactic budge.<ref>http://adsabs.harvard.edu/abs/1976AJ.....81.1095H</ref> Both types of globular cluster populations have been found in several galaxies, being most common in large [[elliptical galaxy|elliptical galaxies]]. What causes the difference between the two types of clusters is not exactly known. Some scenarios to explain this include galaxy mergers, the absorption of satellite galaxies, and staggered star formation within galaxies.<ref>http://adsabs.harvard.edu/abs/2002astro.ph..7607Y</ref>

Globular clusters are generally believed to be around 9 to 13 billion years in age and initially form as a loose collection of stars. As the cluster passes into "adolescence", the stars near the center of the cluster begin to collapse in towards each other. This collapse ends when the interaction of [[binary star|binary systems]] prevent any further contraction, at this point the cluster is at "middle age". Eventually over time, stars in the binary systems are ejected by gravitational disruption as the cluster passes through "old age". It is believed that virtually all globular clusters are far along in the "old age" portion of their evolution. However a more recent study of 13 globular clusters suggests though that some of the clusters may actually be much younger then initially believed. This is due to the fact that three of the clusters were found to still have a large number of [[x-ray]] binaries, suggesting that not enough time has passed to eject many binary companions from the cluster. If these new observations are confirmed, this would challenge the current theories on the evolution of such clusters.<ref>http://www.astronomynow.com/Oldglobularclusterssurprisinglyyoung.html</ref>

[[Category: Astronomy]]

==References==
{{reflist}}

Crab Nebula

2010-01-27T20:06:58Z

BMcP: Added a reference

{{Night Sky
| image =Hubble Crab Nebula.JPG
| designation =M1 NGC 1952
| rightascension =05h 34m 31.97s
| declination =+22o 00′ 52.1"
| distance =6,500 ± 1,600 ly
| constellation =[[Taurus]]
| type =[[nebula]], [[supernova|supernova remnant]]
| dimensions =6x4 (arc min)
| magnitude =Apparent Mag: +8.4 Absolute Mag: −3.1 ± 0.5
| redshift =
| radvelocity =
| propmotion =
| parallax =
}}

The '''Crab Nebula''', also know as '''M1''' and '''NGC 1952''', is an expanding gas cloud surrounding a [[neutron star]] located in the constellation of [[Taurus]] near the star [[Zeta Tauri]], the south horn of the bull. Possibly the most famous [[nebula]], it is the result of a [[supernova]] event that was first observed on [[Earth]] in 1054 A.D. Since then, the nebula has been expanding at a rate of 1500 km/s and is now on average some 11 light years in diameter<ref>http://apod.nasa.gov/apod/ap011227.html</ref>.

==Supernova Event==

The Crab Nebula is the result of the supernova event called '''SN1054''', which was first recorded by [[Chinese]] and [[Arab]] astronomers on July 4th, 1054 A.D. as a "guest star". The event was possibly also the inspiration for astronomy related art created by [[Anasazi]] [[Indians]].<ref>http://www.astronomy.pomona.edu/archeo/outside/chaco/nebula.html</ref> Initially the supernova had an apparent magnitude of -6, making it brighter then even [[Venus]]. The star then began to fade, but remained subsequently bright enough to be observed during the day for the next 23 days, and at night for the next 653 days before finally fading from view.<ref>http://www.seds.org/messier/more/m001_sn.html</ref> The supernova has been classified since with the variable star designation '''CM Tauri'''.

The progenitor star for the explosion is calculated to be between 9 and 11 solar masses, this is based on theoretical models of supernova explosions.<ref>http://adsabs.harvard.edu/abs/1985cnrs.work...97N</ref>

==History of Observation==
[[Image:CrabNebula.jpg|thumb|left|250px|This image from the Chandra X-Ray Observatory shows the central pulsar of the Crab Nebula surrounded by tilted rings of high-energy particles.]]
The first person to discover the nebula remnant was [[English]] astronomer [[John Bevis]] in 1731, who recorded it in his book, ''Uranographia Britannica''. Later in 1758, [[Charles Messier]] discovered the nebula independently while he was searching for [[Halley's Comet]], and initially mistook the nebula for another [[comet]]. He soon realized it wasn't, when it became apparent it lacked any proper motion, and it became the first astronomical object recorded in his famous ''Catalogue des Nébuleuses et des Amas d'Étoiles'' ("Catalogue of Nebulae and Star Clusters").

The name "Crab Nebula" itself originated from a drawing of the nebula made by '''Lord Rosse''' in 1844, where the supernova remnant looked like a crab.<ref>http://seds.org/MESSIER/more/m001_rosse.html</ref>

In 1892 the first [[photograph]] was taken of the nebula using a 20 inch [[telescope]]. Later in 1921 it was discovered that the nebula was expanding at a rate that allowed for the tracing of its origin to about 900 years before.<ref>http://adsabs.harvard.edu/abs/1921PNAS....7..179D</ref> Meanwhile, independently in the same year it was realized that the nebula was also in the same proximity as the supernova SN1054, these two observations lead to the revelation the nebula was the remnant of that same supernova event.<ref>http://adsabs.harvard.edu/abs/1921PASP...33..225L</ref>

Later in 1949, the nebula was discovered to be a strong source of [[radio waves]].<ref>http://adsabs.harvard.edu/abs/1949Natur.164..101B</ref> In 1963 it was discovered the nebula was also a major source of [[x-rays|x-ray]], emitting x-ray [[radiation]] at 100 times the energy the nebula emits energy in the visual spectrum.<ref>http://www.sciencemag.org/cgi/content/abstract/146/3646/912</ref> Eventually the source of this energy was discovered in 1968, when a radio [[pulsar]], later revealed to be a neutron star, was found.

==Properties==

Despite being one of the best known nebula, the Crab Nebula isn't visible to the unaided eye with an apparent magnitude of only +8.4 The exact distance of the nebula itself is uncertain but is estimated around 6,500 ± 1,600 light years away.<ref>http://adsabs.harvard.edu/abs/2008arXiv0801.1142K</ref> It is roughly some 11 light years across overall, extending some 13 light years across at its longest. Right now the nebula's gasses are expanding at around 1500 km/s, and is believed accelerating due to energy emitting from the pulsar. The amount of matter in the nebula is estimated to be around 4.6 ± 1.8 solar masses, and is used to help estimate the total mass of the progenitor star.<ref>http://adsabs.harvard.edu/abs/1997AJ....113..354F</ref>

===Crab Pulsar===

The '''Crab Pulsar''' is a a rapidly rotating [[neutron star]] some 28-30 kilometers in diameter, and has a mass twice that of the [[Sun]]. <ref>http://adsabs.harvard.edu/abs/2002A%26A...396..917B</ref> The pulsar rotates once every 33 milliseconds, emitting radiation towards us once per rotation. This allows us to measure its rotational speed at 6.4 million km/h. The pulsar is slowing down though, rotating 15 microseconds slower each year. The [[radiation]] emitted though from the remnant pulsar is enough to illuminate the entire Crab Nebula with a total luminosity some 75,000 time greater then our Sun.<ref>http://www.solstation.com/x-objects/crab-neb.htm</ref>

[[Category:Astronomy]]

==References==
{{reflist}}

Globular cluster

2010-01-26T20:00:19Z

BMcP: Added image request

{{image request}}
A '''globular cluster''' is a spherical grouping of [[star|stars]] that share a common origin and orbits the galactic core of a [[galaxy]] as a satellite. They are very tightly bound by [[gravity]] and contain anywhere from tens of thousands to million of stars in an area that is only some 300 light years across or less, and are generally oblate spheroids in shape. The density of the clusters are on average around 0.4 stars per cubic [[parsec]], but increases toward to the center of the cluster, reaching as high as 100 or even a 1000 stars per cubic parsec.<ref>http://www.astro.keele.ac.uk/workx/globulars/globulars.html</ref>

Unlike [[open cluster|open clusters]], which contain [[metallicity|younger population I stars]] and reside in the [[galactic disk]], globular clusters are made up of older population II stars and are found in either the [[galactic bulge]] or [[galactic halo]]. Some globular clusters are found as far out as 131,000 light years from the core of the galaxy.<ref>http://adsabs.harvard.edu/abs/1996A&A...313..119D</ref> Current, there are 158 known globular clusters around the [[Milky Way]], with several more perhaps yet to be discovered, all moving in highly eccentric orbits.<ref>http://www.seds.org/~spider/spider/MWGC/mwgc.html</ref> Beyond the Milky Way, most other galaxies in the Local Group and beyond have globular clusters. [[Andromeda_galaxy|Andromeda]] is known to have some 500.

==History==

Abraham Ihle, an amateur [[astronomer]] from [[Germany]] was the first to discover a globular cluster when he found the cluster M22 in 1665, however at the time his telescope was not able to resolve the individual stars. [[Charles Messier]] was the first to identify globular clusters as being made up of individual stars when he observed the cluster M4. It was [[William Herschel]] though who first coined the term globular cluster in his catalog of deep sky objects in 1789. Herschel also discovered 37 such clusters alone, as well as fully resolve the stars in 33 previous discovered ones.

In 1918, [[Harlow Shapley]] used his studies of globular clusters and their asymmetrical distribution in the galaxy to calculate both the distance of the [[Sun]] to the galactic center, and the overall dimensions of the [[Milky Way]] itself. Although the measurements he made were off from the actual size of the galaxy, due to not taking into account dust in the Milky Way diminishing light from the various clusters, he did in fact show the galaxy was much larger then previously believed.<ref>http://adsabs.harvard.edu/abs/1918PASP...30...42S</ref>

==Age and Composition==

The stars themselves that make up globular clusters are all metal-poor population II stars, older stars similar to those located in the central budge of the Milky Way. There is also no detectable gas or dust in these clusters suggesting that all such material had long ago been used up to create stars.

Globular clusters are future divided into two major groupings known as ''Oosterhoff groups'', the difference between the level of [[metallicity]] found in the stars in the cluster. Clusters of the type I group are found to have somewhat weak metal absorption line in their spectra, while Type II have very weak metal lines. As such, Type I clusters are referred to as "metal-rich" and Type II as "metal-poor". Both types are metal-poor in comparison to younger population I stars found in the [[galactic disk]].<ref>van Albada, T. S.; Baker, Norman (1973). "On the Two Oosterhoff Groups of Globular Clusters". Astrophysical Journal 185: 477–498. do:10.1086/152434.</ref> In the Milky Way, the more metal-poor type II clusters are located in the outer part of the galactic halo, while the more metal-rich clusters are found near the galactic budge.<ref>http://adsabs.harvard.edu/abs/1976AJ.....81.1095H</ref> Both types of globular cluster populations have been found in several galaxies, being most common in large [[elliptical galaxy|elliptical galaxies]]. What causes the difference between the two types of clusters is not exactly known. Some scenarios to explain this include galaxy mergers, the absorption of satellite galaxies, and staggered star formation within galaxies.<ref>http://adsabs.harvard.edu/abs/2002astro.ph..7607Y</ref>

Globular clusters are believed to be around 9 to 13 billion years in age and initially form as a loose collection of stars. As the cluster passes into "adolescence", the stars near the center of the cluster begin to collapse in towards each other. This collapse ends when the interaction of [[binary star|binary systems]] prevent any further contraction, at this point the cluster is at "middle age". Eventually over time, stars in the binary systems are ejected by gravitational disruption as the cluster passes through "old age". It is believed that virtually all globular clusters are far along in the "old age" portion of their evolution. However a more recent study of 13 globular clusters suggests though that some of the clusters may actually be much younger then initially believed. This is due to the fact that three of the clusters were found to still have a large number of [[x-ray]] binaries, suggesting that not enough time has passed to eject many binary companions from the cluster. If these new observations are confirmed, this would challenge the current theories on the evolution of such clusters.<ref>http://www.astronomynow.com/Oldglobularclusterssurprisinglyyoung.html</ref>

[[Category: Astronomy]]

==References==
{{reflist}}

Globular cluster

2010-01-26T19:59:28Z

BMcP: Created page with 'A '''globular cluster''' is a spherical grouping of stars that share a common origin and orbits the galactic core of a galaxy as a satellite. They are very tightly ...'

A '''globular cluster''' is a spherical grouping of [[star|stars]] that share a common origin and orbits the galactic core of a [[galaxy]] as a satellite. They are very tightly bound by [[gravity]] and contain anywhere from tens of thousands to million of stars in an area that is only some 300 light years across or less, and are generally oblate spheroids in shape. The density of the clusters are on average around 0.4 stars per cubic [[parsec]], but increases toward to the center of the cluster, reaching as high as 100 or even a 1000 stars per cubic parsec.<ref>http://www.astro.keele.ac.uk/workx/globulars/globulars.html</ref>

Unlike [[open cluster|open clusters]], which contain [[metallicity|younger population I stars]] and reside in the [[galactic disk]], globular clusters are made up of older population II stars and are found in either the [[galactic bulge]] or [[galactic halo]]. Some globular clusters are found as far out as 131,000 light years from the core of the galaxy.<ref>http://adsabs.harvard.edu/abs/1996A&A...313..119D</ref> Current, there are 158 known globular clusters around the [[Milky Way]], with several more perhaps yet to be discovered, all moving in highly eccentric orbits.<ref>http://www.seds.org/~spider/spider/MWGC/mwgc.html</ref> Beyond the Milky Way, most other galaxies in the Local Group and beyond have globular clusters. [[Andromeda_galaxy|Andromeda]] is known to have some 500.

==History==

Abraham Ihle, an amateur [[astronomer]] from [[Germany]] was the first to discover a globular cluster when he found the cluster M22 in 1665, however at the time his telescope was not able to resolve the individual stars. [[Charles Messier]] was the first to identify globular clusters as being made up of individual stars when he observed the cluster M4. It was [[William Herschel]] though who first coined the term globular cluster in his catalog of deep sky objects in 1789. Herschel also discovered 37 such clusters alone, as well as fully resolve the stars in 33 previous discovered ones.

In 1918, [[Harlow Shapley]] used his studies of globular clusters and their asymmetrical distribution in the galaxy to calculate both the distance of the [[Sun]] to the galactic center, and the overall dimensions of the [[Milky Way]] itself. Although the measurements he made were off from the actual size of the galaxy, due to not taking into account dust in the Milky Way diminishing light from the various clusters, he did in fact show the galaxy was much larger then previously believed.<ref>http://adsabs.harvard.edu/abs/1918PASP...30...42S</ref>

==Age and Composition==

The stars themselves that make up globular clusters are all metal-poor population II stars, older stars similar to those located in the central budge of the Milky Way. There is also no detectable gas or dust in these clusters suggesting that all such material had long ago been used up to create stars.

Globular clusters are future divided into two major groupings known as ''Oosterhoff groups'', the difference between the level of [[metallicity]] found in the stars in the cluster. Clusters of the type I group are found to have somewhat weak metal absorption line in their spectra, while Type II have very weak metal lines. As such, Type I clusters are referred to as "metal-rich" and Type II as "metal-poor". Both types are metal-poor in comparison to younger population I stars found in the [[galactic disk]].<ref>van Albada, T. S.; Baker, Norman (1973). "On the Two Oosterhoff Groups of Globular Clusters". Astrophysical Journal 185: 477–498. do:10.1086/152434.</ref> In the Milky Way, the more metal-poor type II clusters are located in the outer part of the galactic halo, while the more metal-rich clusters are found near the galactic budge.<ref>http://adsabs.harvard.edu/abs/1976AJ.....81.1095H</ref> Both types of globular cluster populations have been found in several galaxies, being most common in large [[elliptical galaxy|elliptical galaxies]]. What causes the difference between the two types of clusters is not exactly known. Some scenarios to explain this include galaxy mergers, the absorption of satellite galaxies, and staggered star formation within galaxies.<ref>http://adsabs.harvard.edu/abs/2002astro.ph..7607Y</ref>

Globular clusters are believed to be around 9 to 13 billion years in age and initially form as a loose collection of stars. As the cluster passes into "adolescence", the stars near the center of the cluster begin to collapse in towards each other. This collapse ends when the interaction of [[binary star|binary systems]] prevent any further contraction, at this point the cluster is at "middle age". Eventually over time, stars in the binary systems are ejected by gravitational disruption as the cluster passes through "old age". It is believed that virtually all globular clusters are far along in the "old age" portion of their evolution. However a more recent study of 13 globular clusters suggests though that some of the clusters may actually be much younger then initially believed. This is due to the fact that three of the clusters were found to still have a large number of [[x-ray]] binaries, suggesting that not enough time has passed to eject many binary companions from the cluster. If these new observations are confirmed, this would challenge the current theories on the evolution of such clusters.<ref>http://www.astronomynow.com/Oldglobularclusterssurprisinglyyoung.html</ref>

[[Category: Astronomy]]

==References==
{{reflist}}