HD 129116
HD 129116 is a binary star in the northeastern part of Centaurus, east of Menkent. It is also known by its Bayer designation of b Centauri, while HD 129116 is the star's identifier in the Henry Draper catalogue. This object has a blue-white hue and is faintly visible to the naked eye with an apparent visual magnitude of +4.01. It is located at a distance of approximately 325 light years (100 parsecs) from the Sun based on parallax, and has an absolute magnitude of −1.07.
b Centauri imaged by VLT/SPHERE. The planet b Centauri b is indicated by an arrow. Credit: ESO/Janson et al. | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Centaurus |
| Right ascension | 14h 41m 57.59068s |
| Declination | −37° 47′ 36.5940″ |
| Apparent magnitude (V) | +4.01 |
| Characteristics | |
| Evolutionary stage | Main sequence |
| Spectral type | B3V |
| B−V color index | −0.157±0.002 |
| Variable type | Constant |
| Astrometry | |
| Radial velocity (Rv) | +2.6±1.5 km/s |
| Proper motion (μ) | RA: −29.828±0.369 mas/yr Dec.: −31.914±0.518 mas/yr |
| Parallax (π) | 10.0339 ± 0.3143 mas |
| Distance | 330 ± 10 ly (100 ± 3 pc) |
| Absolute magnitude (MV) | −1.07 |
| Details | |
| Mass | 5–6 M☉ |
| Radius | 2.93±0.12 R☉ |
| Luminosity | 637.01 L☉ |
| Surface gravity (log g) | 4.23±0.03 cgs |
| Temperature | 18,310±320 K |
| Rotational velocity (v sin i) | 129 km/s |
| Age | 15±2 Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
The primary star is a hot type-B star with a spectral type of B3V and a mass of 5 to 6 times the solar mass. The secondary star is a close companion separated by approximately 1 AU, with up to 4.4 times the solar mass. In 2021, a massive exoplanet was discovered by direct imaging orbiting the pair of stars (a circumbinary planet) at a distance of about 560 AU.