| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Auriga |
| Right ascension | 05h 16m 27.08298s[1] |
| Declination | +46° 24′ 57.8118″[1] |
| Apparent magnitude (V) | 6.988[2] |
| Characteristics | |
| Spectral type | B2 Ve[3] |
| Astrometry | |
| Proper motion (μ) | RA: −3.321[1]mas/yr Dec.: −1.2106[1]mas/yr |
| Parallax (π) | 1.5264±0.0303 mas[1] |
| Distance | 2,140 ± 40 ly (660 ± 10 pc) |
| Details | |
| Mass | 3.0[4] M☉ |
| Radius | 18[5] R☉ |
| Luminosity | 635[5] L☉ |
| Surface gravity (log g) | 2.47[4] cgs |
| Temperature | 8,688[6] K |
| Metallicity | −0.94[4] |
| Rotational velocity (v sin i) | 100±41[7] km/s |
| Other designations | |
| 12 Aur,BD+46°989,GC 6424,HD 33988,SAO 40183,PPM 47919[8] | |
| Database references | |
| SIMBAD | data |
12 Aurigae is aBe star in the northernconstellationAuriga. It lies below the normal limit for visibility to the naked eye, having anapparent visual magnitude of 6.988.[2] It lacks a designation from theHipparcos catalogue. It is located just under half a degree north ofCapella.[8]
Assignedspectral classes for 12 Aurigae vary greatly from B2 to B5 and theluminosity class from V (main sequence) to Ia (luminoussupergiant). Itsspectrum shows prominentemission lines, but the spectrum is complicated by the appearance of sharpshell components to some of the spectral lines.[9] The colour of the star as shown by the B-V and U-Bcolour indices is not consistent with an early B spectral class,[10] leading to many estimates of itseffective temperature that are much lower than expected for a B-class star.[6][4] The expected temperature for a B5 spectral type would be15,400 K,[11] but most sources assign a temperature of around8,000 K.[6][4] Other properties also vary between different sources, for example thebolometric luminosity derived from the distance and temperature is 25 L☉,[6] while it is 635 L☉ when derived by fitting thespectral energy distribution.[5] A calculation of the stellar properties assuming the maximum possibleinterstellar extinction in the direction of 12 Aurigae results in a temperature of14,336 K and a luminosity of 8,092 L☉, although it is strongly noted that the likely extinction is much lower.[5]
