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[[Image:{{Night Sky| image =Gemini constellation map.png|thumbdesignation =HD 62509<br/>HIP 37826|rightrightascension =07^h 45^m 18.94987^s<ref name=simbad>[http://simbad.u-strasbg.fr/simbad/sim-id?Ident=pollux&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id pollux] from the [http://simbad.u-strasbg.fr/simbad SIMBAD Astronomical Database]</ref>|338pxdeclination =+28° 01′ 34.3160″<ref name=simbad/>|Location of Pollux in the distance =33.78 ly<ref name=cons>{{cite web|url=http://www.constellation of -guide.com/constellation-list/gemini-constellation/|title=Gemini]]Constellation|accessdate=2018-12-22}}</ref>| constellation =Gemini| type =Star| dimensions =| 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>| redshift =| radvelocity =3.23±0.02 km/s<ref name=simbad/>| propmotion =RA: -626.55 mas/yr<ref name=simbad/><br/>Dec.: -45.80 mas/yr<ref name=simbad/>| parallax =96.54±0.27 mas<ref name=simbad/>}}'''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.

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*.htmlpenelope.uchicago.edu]</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>httpAllende 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/cgi-bin#abs/nph-bib_query?bibcode=2000ApJ...528..885A&db_key=AST&data_type=HTML&format=&high=44a287269c18839Bibcode: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 4770 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 elements [[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]].

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/0606517arXiv: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 AU from Pollux, equivalent to [[Jupiter]]'s orbit of the Sun. [[Category:Astronomy]]

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