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[[Image:Gemini constellation map.png|thumb|right|338px|Location of Pollux in the constellation of Gemini]]

'''Pollux''', also called '''Beta Geminorium''', is an orange giant located in the constellation [[Gemini]] 33.7 light years away. Although Pollux has the [[Bayer designation]] of Beta, ([[Castor]] having the Alpha designation) it is actually the brightest star in the constellation. Pollux is the 17th brightest star overall in the night sky with an apparent magnitude of 1.15. In 2006 it was confirmed that Pollux has one known extrasolar planet in orbit.

| image          =Gemini constellation map.png

| declination    =+28° 01′ 34.3160″<ref name=simbad/>

| distance        =33.78 ly<ref name=cons>{{cite web|url=http://www.constellation-guide.com/constellation-list/gemini-constellation/|title=Gemini Constellation|accessdate=2018-12-22}}</ref>

| constellation   =Gemini

| magnitude      =Apparent Mag: +1.14<ref name=cons/><br/>Absolute Mag: +1.06<ref>From definition of absolute magnitude, using apparent magnitude (+1.14) and distance (33.78 ly) given here.</ref>

'''Pollux''', also called '''Beta Geminorium''', is an orange giant located in the [[constellation]] [[Gemini]] 33.7 light years away. Although Pollux has the [[Bayer designation]] of Beta, ([[Castor]] having the Alpha designation) it is actually the brightest star in the constellation. Pollux is the 17th brightest star overall in the night sky with an apparent magnitude of 1.15. In 2006 it was confirmed that Pollux has one known [[extrasolar planet]] in orbit.

==Star Name==

==Star Name==

The name Pollux is based on the twins Pollux and Castor of [[Greek mythology]], who were the twin sons of [[Zeus]] and Leda.   The original name in classical [[Greece]] for Pollux was Πολυδευκής or ''Polydeuces''. [[Ptolemy]] though liked to refer to the star using the word ὑπόκιρρος, which described the star as "yellowish" or "reddish", and not as a formal name.  In [[Arabic]], the star is called الرأس التؤام المؤخر or ''Al-Ras al-Tau'am al-Mu'akhar'', meaning "The Head of the Second Twin".<ref>http://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Gemini*.html</ref>

The name Pollux is based on the twins Pollux and Castor of [[Greek mythology]], who were the twin sons of [[Zeus]] and Leda. The original name in classical [[Greece]] for Pollux was Πολυδευκής or ''Polydeuces''. [[Ptolemy]] though liked to refer to the star using the word ὑπόκιρρος, which described the star as "yellowish" or "reddish", and not as a formal name.  In [[Arabic]], the star is called الرأس التؤام المؤخر or ''Al-Ras al-Tau'am al-Mu'akhar'', meaning "The Head of the Second Twin".<ref>Allen, Richard Hinkley (1963). Star Names, Their Lore and Meaning. New York: Dover. ISBN 0-486-21079-0. Avaliable online at: [http://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Gemini*.html penelope.uchicago.edu]</ref>

==The Star==

==The Star==

Pollux is an orange-red giant with a spectral classification of K0 IIIb. The [[star]] is 8.8 times the diameter of our [[Sun]]. However like all giants, it has a low mass - being only 1.7 times as massive as our own star.<ref>http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2000ApJ...528..885A&db_key=AST&data_type=HTML&format=&high=44a287269c18839</ref>  Pollux is 32 times as visually luminous as our Sun, with a total luminosity 46 times as great when accounting for the [[infrared]]. As a cooler class K giant, Pollux has a surface temperature of around 4770 K.<ref>http://stars.astro.illinois.edu/sow/pollux.html</ref> The star has a [[metallicity]] (abundance of elements heavier then [[hydrogen]] and [[helium]]) between 85 and 155 percent of that of our Sun, based on the abundance of iron measured.<ref>http://www.solstation.com/stars2/pollux.htm</ref>  

Pollux is an orange-red giant with a spectral classification of K0 IIIb. The [[star]] is 8.8 times the diameter of our [[Sun]]. However like all giants, it has a low mass - being only 1.7 times as massive as our own star.<ref>Allende Prieto, C., Garcia Lopez, R., Lambert, D. and Ruiz Cobo, B. (2000). Model Photospheres for Late-Type Stars from the Inversion of High-Resolution Spectroscopic Observations: Groombridge 1830 and ε Eridani. ''The Astrophysical Journal'', 528(2), pp.885-895. [https://ui.adsabs.harvard.edu/#abs/2000ApJ...528..885A Bibcode:2000ApJ...528..885A]</ref>  Pollux is 32 times as visually luminous as our Sun, with a total luminosity 46 times as great when accounting for the [[infrared]]. As a cooler class K giant, Pollux has a surface temperature of around 4,770 K.<ref>{{cite web|url=http://stars.astro.illinois.edu/sow/pollux.html|title=Pollux|accessdate=2018-12-22}}</ref> The star has a [[metallicity]] (abundance of [[element]]s heavier then [[hydrogen]] and [[helium]]) between 85 and 155 percent of that of our Sun, based on the abundance of [[iron]] measured.<ref>{{cite web|url=http://www.solstation.com/stars2/pollux.htm|title=Pollux|accessdate=2018-12-22}}</ref>  

The star itself has used up all its core hydrogen fuel and has shifted to fusing helium in its core to [[carbon]] and [[oxygen]]. This lose of mass will puff out from the star as a planetary nebula, consisting mostly of hydrogen and helium, with some heavier elements (such as carbon and oxygen). Once this occurs, the resultant left over star will be a [[white dwarf]].

The star itself has used up all its core hydrogen fuel and has shifted to fusing helium in its core to [[carbon]] and [[oxygen]]. This lose of mass will puff out from the star as a [[planetary nebula]], consisting mostly of hydrogen and helium, with some heavier elements (such as carbon and oxygen). Once this occurs, the resultant left over star will be a [[white dwarf]].

==Planetary System==

==Planetary System==

Pollux has one confirmed extrasoloar planet in orbit. The planet, unofficially called "Polydeuces" was first detected in 1993, but was not confirmed until June 16, 2006.  Polydeuces is a [[Jupiter]] class [[gas giant]] with a minimum mass of 2.3 times Jupiter's.  The orbit of Pollux has an average distance of 1.64 AU, and takes around 1.6 years to complete.<ref>http://lanl.arxiv.org/abs/astro-ph/0606517</ref>

Pollux has one confirmed extrasoloar planet in orbit. The planet, unofficially called "Polydeuces" was first detected in 1993, but was not confirmed until June 16, 2006.  Polydeuces is a [[Jupiter]] class [[gas giant]] with a minimum mass of 2.3 times Jupiter's.  The orbit of Pollux has an average distance of 1.64 AU, and takes around 1.6 years to complete.<ref>Hatzes, A., Cochran, W., Endl, M., Guenther, E., Saar, S., Walker, G., Yang, S., Hartmann, M., Esposito, M., Paulson, D. and Döllinger, M. (2006). Confirmation of the planet hypothesis for the long-period radial velocity variations of β Geminorum. ''Astronomy & Astrophysics'', 457(1), pp.335-341. [http://lanl.arxiv.org/abs/astro-ph/0606517 arXiv:astro-ph/0606517]</ref>

For an [[terrestrial planet|Earth-like]] world to have liquid [[water]] on its surface, it would need to be centered around 5.7 Au from Pollux, equivalent to Jupiter's orbit of the Sun.

For an [[terrestrial planet|Earth-like]] world to have liquid [[water]] on its surface, it would need to be centered around 5.7 AU from Pollux, equivalent to [[Jupiter]]'s orbit of the Sun.

 

==References==

==References==

{{reflist}}

{{reflist}}

==Links==

==External links==

*[http://exoplanet.eu/ Extrasolar Planets Encyclopaedia]

*[http://exoplanet.eu/ Extrasolar Planets Encyclopaedia]

*[http://exoplanets.org/ ExoPlanets]

*[http://exoplanets.org/ ExoPlanets]

*[http://stars.astro.illinois.edu/sow/pp.html The Planet Project]

*[http://stars.astro.illinois.edu/sow/pp.html The Planet Project]