Eta Canis Majoris
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Eta Canis Majoris (η Canis Majoris, abbreviated Eta CMa, η CMa), also named Aludra Template:IPAc-en,<ref name="IAU-CSN">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> is a blue supergiant star in the constellation of Canis Major. It has an apparent magnitude varying between 2.38 and 2.48, which makes it the fifth-brightest in the constellation and brightest stars. Parallax measurements from the Hipparcos mission give a large distance of 2,000 light-years.
NomenclatureEdit
η Canis Majoris (Latinised to Eta Canis Majoris) is the star's Bayer designation.
The traditional name Aludra originates from the Arabic: العذراء al-adhraa, 'the virgin'. This star, along with Epsilon Canis Majoris (Adhara), Delta Canis Majoris (Wezen) and Omicron2 Canis Majoris (Thanih al Adzari), were Al 'Adhārā (العذاري), 'the Virgins'.<ref name=allen1963/> In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)<ref name="WGSN"/> to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016<ref name="WGSN1"/> included a table of the first two batches of names approved by the WGSN; which included Aludra for this star.
In Chinese, {{#invoke:Lang|lang}} ({{#invoke:Lang|lang}}), meaning Bow and Arrow,<ref name=KooShe/> refers to an asterism consisting of Eta Canis Majoris, Delta Canis Majoris, HD 63032, HD 65456, Omicron Puppis, k Puppis, Epsilon Canis Majoris, Kappa Canis Majoris and Pi Puppis. Consequently, Eta Canis Majoris itself is known as {{#invoke:Lang|lang}} ({{#invoke:Lang|lang}}, Template:Langx).<ref name=AEEA/>
PropertiesEdit
Eta Canis Majoris is a blue supergiant with a spectral type B5Ia. It has been the standard for this spectral class in the Morgan–Keenan system, and since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified.<ref name=baas25_1319/><ref name=morgan1978/>
It is likely a post-red supergiant, a star which left its red supergiant phase and is near the end of its life. As a consequence, Aludra has lost significant part of its mass, it started with a mass of Template:Solar mass and now has either Template:Solar mass, depending on the estimate.<ref name=Sanchez2023/>
Aludra shines brightly in the skies in spite of a large distance from Earth due to being intrinsically many times brighter than the Sun. It has a luminosity over 100,000 times and a radius around 54 times that of the Sun. It has only existed for a fraction of the time the Sun has, less than 10 million years, yet is already in the last stages of its life.<ref name=haucke2018/><ref name=Sanchez2023/>
The star is classified as an Alpha Cygni-type variable star and its brightness varies from magnitude +2.38 to +2.48 over a period of 4.7 days.<ref name=Kazarovets/><ref name=AAVSOeta/>
NamesakesEdit
Both USS Aludra (AF-55), an Alstede-class stores ship, and USS Aludra (AK-72), a Crater-class cargo ship, were U.S. Navy vessels named after the star.