Beta Aurigae

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Beta Aurigae A / B / C
Observation data
Epoch J2000.0
Constellation
(pronunciation)
Auriga
Right ascension 05h 59m 31.7s
Declination +44° 56′ 51″
Apparent magnitude (V) +1.90 (2.56/2.8/10.6)
Characteristics
Spectral type A2IV / A2IV / MV
U-B color index +0.05
B-V color index +0.03
Variable type Algol variable
Astrometry
Radial velocity (Rv) −18.2 km/s
Proper motion (μ) RA: −56.41 mas/yr
Dec.: −0.88 mas/yr
Parallax (π) 39.72 ± 0.78 mas
Distance 82.1 ly (25.2 pc)
Absolute magnitude (MV) −0.11
Details
Mass ? M
Radius 3 R
Luminosity 95 L
Temperature 8,800 K
Metallicity 100% Sun
Rotation 37 km/s
Age ? years
Other designations
Menkalinan, Menkarlina, 34 Aurigae, HR 2088, BD +44°1328, HD 40183, SAO 40750, NN 3375, GC 7543, FK5 227, ADS 4556, CCDM 05596+4457, HIP 28360
Database references
SIMBAD data

Beta Aurigae (β Aur / β Aurigae), traditionally named Menkalinan (also written as Menkarlina), is a white subgiant star approximately 85 light-years away in the constellation Auriga.

The name Menkalinan is shortened from the Arabic منكب ذي العنان mankib ðī-l-‘inān "shoulder of the rein-holder".

Beta Aurigae is a white star of spectral class A , similar to Vega, Denebola, and Sirius. Beta Aurigae is also a subgiant star, which means it has started to change from burning hydrogen to burning helium, has moved off the main sequence, and is slowly expanding into a giant star like Aldebaran.

Beta Aurigae is actually a ternary (triple) star system. The two brightest components, Beta Aurigae A and B, are both white subgiants. Star B is about the same mass and radius as A. Beta Aurigae A and B form an eclipsing spectroscopic binary; the combined apparent magnitude varies over a period of 3.96004 days between +1.85 and +1.93, as every 47.5 hours one of the stars partially eclipses the other from Earth's perspective. The third star, Beta Aurigae C, is a red dwarf star that is far below naked-eye visibility. It is about 330 AU from the AB pair.

Beta Aurigae is believed to be a stream star member of the Ursa Major Moving Group. It is known as 五車三 (the Third Star of the Five Chariots) in Chinese

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