Gamma Geminorum
Gamma Geminorum (γ Geminorum, abbreviated Gamma Gem, γ Gem), formally named Alhena , is the third-brightest object in the constellation of Gemini. It has an apparent visual magnitude of 1.9, making it easily visible to the naked eye even in urban regions. Based upon parallax measurements with the Hipparcos satellite, it is located at a distance of roughly from the Sun. Properties. Alhena is an evolving star that is exhausting the supply of hydrogen at its core and has entered the subgiant stage. The spectrum matches a stellar classification of A0 IV. Compared to the Sun it has  2.8 times the mass and 3.3 times the radius. It is radiating around 123 times the luminosity of the Sun from its outer envelope at an effective temperature of 9,260 K. This gives it a white hue typical of an A-class star. Alhena is a spectroscopic binary system with a period of 12.6 years (4,614.51 days) in a highly eccentric Keplerian orbit. The secondary, with 1.07 times the mass of the Sun, is likely a G-type main-sequence star. Etymology. "γ Geminorum" (Latinised to "Gamma Geminorum") is the star's Bayer designation. The traditional name "Alhena" is derived  from the Arabic الهنعة "Al Han'ah", 'the brand' (on the neck of the camel), whilst the alternate name "Almeisan" is from the Arabic المیسان "Al Maisan", 'the shining one.' "Al Hanʽah" was the name of star association consisting of this star, along with Mu Geminorum (Tejat Posterior), Nu Geminorum, Eta Geminorum (Tejat Prior) and Xi Geminorum (Alzirr). They also were associated in "Al Nuḥātai", the dual form of "Al Nuḥāt", 'a Camel's Hump'. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN's first  bulletin of July 2016 included a table of the first two batches of names approved by the WGSN; which included "Alhena" for this star. In the catalogue of stars in the "Calendarium of Al Achsasi Al Mouakket", this star was designated "Nir al Henat", which was translated into Latin as "Prima του al Henat", meaning 'the brightest of Al Henat'. In Chinese, (), meaning "Well (asterism)", refers to an asterism consisting of γ Geminorum, ε Geminorum, ζ Geminorum, λ Geminorum, μ Geminorum, ν Geminorum, ξ Geminorum and 36 Geminorum. Consequently, γ Geminorum itself is known as (, .) In culture. "Alhena" was the  name of a Dutch ship that rescued many people from an Italian cruise liner, the "SS Principessa Mafalda", in October 1927. In addition, the American attack cargo ship was named after the star.