Beta Aurigae


Beta Aurigae, officially named Menkalinan, is a binary star system in the northern constellation of Auriga. The combined apparent visual magnitude of the system is 1.9, making it the second-brightest member of the constellation after Capella. Using the parallax measurements made during the Hipparcos mission, the distance to this star system can be estimated as, give or take a half-light-year margin of error.

Nomenclature

β Aurigae is the star system's Bayer designation. The traditional name Menkalinan is derived from the Arabic منكب ذي العنان mankib ðī-l-‘inān "shoulder of the rein-holder". In 2016, the International Astronomical Union organized a Working Group on Star Names 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 Menkalinan for this star.
It is known as 五車三 in traditional Chinese astronomy.

Properties

Beta Aurigae is a binary star system, but it appears as a single star in the night sky. The two stars are metallic-lined subgiant stars belonging to the A-type stellar classification; they have roughly the same mass and radius. A-type entities are hot stars that release a blue-white hued light; these two stars burn brighter and with more heat than the Sun, which is a G2-type main sequence star. The pair constitute an eclipsing spectroscopic binary; the combined apparent magnitude varies over a period of 3.96 days between +1.89 and +1.94, as every 47.5 hours one of the stars partially eclipses the other from Earth's perspective.
At an angular separation of along a position angle of 155° is a companion star that is 8.5 magnitudes fainter than the binary pair. This is a candidate member of Beta Aurigae, which would make it a triple star system. It may be the source of the X-ray emission from the vicinity. The Beta Aurigae system is believed to be a stream member of the Ursa Major Moving Group.