798
edits
Changes
Jump to navigation
Jump to search
Line 1:
Line 1: − [[Image:Hubble Crab Nebula.JPG|right|thumb|300px|Crab Nebula (NASA)]]+ − + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
no edit summary
{{Night Sky
The '''Crab Nebula''' is the remnant of a powerful [[supernova]] observed in [[China]] in the year 1054. It is located in the [[constellation]] [[Taurus]] and is about 6,300 light years away.
| image =Hubble Crab Nebula.JPG
| designation =M1<br/>NGC 1952
| rightascension =05<sup>h</sup> 34<sup>m</sup> 31.97<sup>s</sup>
| declination =+22<sup>o</sup> 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<br/>Absolute Mag: −3.1 ± 0.5
| redshift =
| radvelocity =
| propmotion =
| parallax =
}}
The '''Crab Nebula''', also know as '''M1''' and '''NGC 1952''', is a supernova remnant surrounding a [[neutron star]]. The most famous [[nebula]], it is the result of a [[supernova]] event that was first observed on [[Earth]] in 1054 A.D. The nebula is located around 6,500 light years away in the constellation of [[Taurus]]. At present the expanding nebular is some 11 light years across and growing at a rate of 1500 km/s.
==Supernova Event==
The Crab Nebula is the result of the supernova event called '''SN1054'''. This event 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 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 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==
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. 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]]
[[Category:Astronomy]]
==References==
{{reflist}}