Theta Aurigae
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Auriga |
| Right ascension | 05h 59m 43.27012s |
| Declination | +37° 12′ 45.3047″ |
| Apparent magnitude (V) | 2.62–2.70 |
| Characteristics | |
| Spectral type | A0pSi + F2-5V |
| U−B color index | −0.18 |
| B−V color index | −0.08 |
| R−I color index | −0.06 |
| Variable type | α2 CVn |
| Astrometry | |
| Radial velocity (Rv) | +29.5 km/s |
| Proper motion (μ) | RA: +43.63 mas/yr Dec.: −73.79 mas/yr |
| Parallax (π) | 19.70±0.16 mas |
| Distance | 166 ± 1 ly (50.8 ± 0.4 pc) |
| Absolute magnitude (MV) | −1.05 |
| Details | |
| Mass | 3.24 M☉ |
| Radius | 4.68 R☉ |
| Luminosity | 214 L☉ |
| Surface gravity (log g) | 3.61 cgs |
| Temperature | 10,220 K |
| Rotation | 3.6187 days |
| Rotational velocity (v sin i) | 55 km/s |
| Age | 288 Myr |
| Other designations | |
| Mahasim, 37 Aurigae, BD+37°1380, HD 40312, HIP 28380, HR 2095, SAO 58636, ADS 4566, WDS 05597+3713 | |
| Database references | |
| SIMBAD | data |
Theta Aurigae is a binary star system in the constellation of Auriga. Its name is a Bayer designation that is Latinized from θ Aurigae, and abbreviated Theta Aur or θ Aur. This is a variable star with an apparent visual magnitude that varies from 2.62 to 2.70, which is bright enough to be seen with the naked eye. Based upon parallax measurements, the distance to this system is about 166 light-years (51 parsecs). It is drifting further away from the Sun with a mean radial velocity of +29.5 km/s.
The two components are designated Theta Aurigae A and B. The former star is the primary and has the proper name Mahasim.