Omicron Aurigae

Omicron Aurigae is an astrometric binary^[9] star system in the northern constellation of Auriga. Its name is a Bayer designation that is Latinized from ο Aurigae, and abbreviated Omicron Aur or ο Aur. With an apparent visual magnitude of 5.47,^[3] it is faintly visible to the naked eye. Based upon an annual parallax shift of 8.19 mas,^[2] it is approximately 400 light-years (120 parsecs) distant from Earth. It is drifting closer to the Sun with a radial velocity of −8 km/s.^[6] The star is a member of the Ursa Major stream of co-moving stars.^[10]

Omicron Aurigae

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Auriga[1]
Right ascension	05h 45m 54.042s[2]
Declination	+49° 49′ 34.58″[2]
Apparent magnitude (V)	+5.47[3]
Characteristics
Spectral type	A1 Cr Eu[4]
U−B color index	+0.02
B−V color index	+0.02[5]
Astrometry
Radial velocity (Rv)	−7.7±0.9[6] km/s
Proper motion (μ)	RA: −11.087 mas/yr[2] Dec.: +3.703 mas/yr[2]
Parallax (π)	8.1876±0.2643 mas[2]
Distance	400 ± 10 ly (122 ± 4 pc)
Absolute magnitude (MV)	−0.03[1]
Details
Mass	1.9[7] M☉
Radius	3.2[7] R☉
Luminosity	50[7] L☉
Surface gravity (log g)	3.7[7] cgs
Temperature	8,300[7] K
Rotational velocity (v sin i)	35.2±5.3[7] km/s
Other designations
ο Aur, 27 Aur, BD+49°1398, FK5 216, HD 38104, HIP 27196, HR 1971, SAO 40583[8]
Database references
SIMBAD	data

The visible component is a chemically peculiar star with a stellar classification of A1 Cr Eu; meaning this is an A-type star with a spectrum that shows anomalously high abundances of chromium (Cr) and europium (Eu).^[4] A magnetic field has been detected and it is a source of X-ray emission with a luminosity of: log L_x = 29.1.^[10] The star has 1.9 times the mass of the Sun and 3.2 times the Sun's radius. It is spinning with a projected rotational velocity of 35 km/s and is radiating 50 times the Sun's luminosity from its photosphere at an effective temperature of 8,300 K.^[7]