Beta Aurigae
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Auriga |
| Right ascension | 05h 59m 31.72293s |
| Declination | +44° 56′ 50.7573″ |
| Apparent magnitude (V) | 1.89–1.98 (2.602 + 2.705) |
| Characteristics | |
| Spectral type | A1m IV + A1m IV |
| U−B color index | +0.05 |
| B−V color index | +0.03 |
| R−I color index | −0.01 |
| Variable type | Algol variable |
| Astrometry | |
| Radial velocity (Rv) | −18.2 km/s |
| Proper motion (μ) | RA: −56.44 mas/yr Dec.: −0.95 mas/yr |
| Parallax (π) | 40.21±0.23 mas |
| Distance | 81.1 ± 0.5 ly (24.9 ± 0.1 pc) |
| Absolute magnitude (MV) | 0.674 / 0.777 |
| Orbit | |
| Period (P) | 3.96004 days |
| Semi-major axis (a) | 0.08214±0.00015 AU |
| Eccentricity (e) | 0.0 |
| Inclination (i) | 76.0 ± 0.4° |
| Periastron epoch (T) | 54539.0162 ± 0.0003 reduced HJD |
| Semi-amplitude (K1) (primary) | 108.053±0.099 km/s |
| Semi-amplitude (K2) (secondary) | 110.911±0.098 km/s |
| Details | |
| β Aur Aa | |
| Mass | 2.3885±0.0134 M☉ |
| Radius | 2.762±0.017 R☉ |
| Luminosity | 46.7+5.7 −5.1 L☉ |
| Surface gravity (log g) | 3.93 cgs |
| Temperature | 8,985 K |
| Rotational velocity (v sin i) | 33 km/s |
| Age | 400–500 Myr |
| β Aur Ab | |
| Mass | 2.327±0.013 M☉ |
| Radius | 2.568±0.017 R☉ |
| Luminosity | 40+10 −8 L☉ |
| Temperature | 8,760 K |
| Rotational velocity (v sin i) | 34 km/s |
| Age | 400–500 Myr |
| Other designations | |
| Menkalinan, β Aurigae, 34 Aurigae, BD+44 1328, FK5 227, GC 7543, HD 40183, HIP 28360, HR 2088, SAO 40750, PPM 48617, ADS 4556, WDS J05595+4457Aa,Ab | |
| Database references | |
| SIMBAD | data |
Beta Aurigae is a binary star system in the northern constellation of Auriga. Its identifier is a Bayer designation that is Latinized from β Aurigae, and abbreviated Beta Aur or β Aur. This star has the official name Menkalinan, pronounced /mɛŋˈkælɪnæn/. 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 81.1 light-years (24.9 parsecs), give or take a half-light-year margin of error. It is drifting closer to the Sun with a radial velocity of −18 km/s.
Along their respective orbits around the Milky Way, Beta Aurigae and the Sun are closing in on each other, so that in around one million years it will become the brightest star in the night sky. It is predicted to come as close as 31.7 ly (9.72 pc) in 1.31 million years.