Beta Centauri
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Centaurus |
| Right ascension | 14h 03m 49.40535s |
| Declination | −60° 22′ 22.9266″ |
| Apparent magnitude (V) | 0.61 |
| Characteristics | |
| U−B color index | −0.98 |
| B−V color index | −0.23 |
| β Cen Aa | |
| Spectral type | B1 III |
| Variable type | β Cep/SPB |
| β Cen Ab | |
| Spectral type | B1 III |
| β Cen B | |
| Spectral type | B1V? |
| Astrometry | |
| Radial velocity (Rv) | +9.59+0.23 −0.21 km/s |
| Proper motion (μ) | RA: −33.27 mas/yr Dec.: −23.16 mas/yr |
| Parallax (π) | 9.04±0.04 mas |
| Distance | 361 ± 2 ly (110.6 ± 0.5 pc) |
| Absolute magnitude (MV) | −4.9±0.2 |
| Orbit | |
| Primary | β Cen Aa |
| Companion | β Cen Ab |
| Period (P) | 356.915±0.015 d (0.97720±0.00004 yr) |
| Semi-major axis (a) | 0.02515+0.09 −0.08″ |
| Eccentricity (e) | 0.8245±0.006 |
| Inclination (i) | 67.68±0.12° |
| Longitude of the node (Ω) | 108.80+0.14 −0.15° |
| Periastron epoch (T) | 2452000.15202 |
| Argument of periastron (ω) (secondary) | 60.87+0.26 −0.25° |
| Semi-amplitude (K1) (primary) | 62.9 km/s |
| Semi-amplitude (K2) (secondary) | 72.35 km/s |
| Orbit | |
| Primary | β Cen A |
| Companion | β Cen B |
| Period (P) | 288.267 yr |
| Semi-major axis (a) | 0.870″ |
| Details | |
| β Cen Aa | |
| Mass | 12.02±0.13 M☉ |
| Radius | 9.16 R☉ |
| Luminosity | 31,600+18,500 −11,700 L☉ |
| Surface gravity (log g) | 3.55±0.11 cgs |
| Temperature | 25,000±2,000 K |
| Rotational velocity (v sin i) | 190±20 km/s |
| Age | 14.1±0.6 Myr |
| β Cen Ab | |
| Mass | 10.58±0.18 M☉ |
| Radius | 8.56 R☉ |
| Luminosity | 25,100+14,700 −9,300 L☉ |
| Surface gravity (log g) | 3.55±0.11 cgs |
| Temperature | 23,000±2,000 K |
| Rotational velocity (v sin i) | 75±15 km/s |
| Age | 14.1±0.6 Myr |
| β Cen B | |
| Mass | 4.61 M☉ |
| Age | 14.1±0.6 Myr |
| Other designations | |
| Agena, Hadar, CD−59°5365, FK5 518, GC 18971, HD 122451, HIP 68702, HR 5267, SAO 252582, CCDM J14038-6022, LHS 51 | |
| Database references | |
| SIMBAD | data |
Beta Centauri is a triple star system in the southern constellation of Centaurus. It is officially called Hadar (/ˈheɪdɑːr/). The Bayer designation of Beta Centauri is Latinised from β Centauri, and abbreviated Beta Cen or β Cen. The system's combined apparent visual magnitude of 0.61 makes it the second-brightest object in Centaurus and the eleventh brightest star in the night sky. According to dynamical parallax measurements, the distance to this system is about 361 light-years (111 parsecs).