HD 102776
HD 102776, also known by its Bayer designation j Centauri, is a suspected astrometric binary star system in the southern constellation of Centaurus. It has a blue-white hue and is faintly visible to the naked eye with a typical apparent visual magnitude of 4.30. The distance to this star is approximately 600 light years based on parallax, and it is drifting further away with a radial velocity of ~29 km/s. It is a member of the Lower Centaurus Crux subgroup of the Sco OB2 association. HD 102776 has a relatively large peculiar velocity of 31.1 km/s and is a candidate runaway star that was ejected from its association, most likely by a supernova explosion.
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Centaurus |
| Right ascension | 11h 49m 41.05745s |
| Declination | −63° 47′ 18.4299″ |
| Apparent magnitude (V) | 4.30 (+4.30 - 4.39) |
| Characteristics | |
| Spectral type | B3V |
| U−B color index | −0.59 |
| B−V color index | −0.15 |
| Variable type | γ Cas |
| Astrometry | |
| Radial velocity (Rv) | +29.0±4.1 km/s |
| Proper motion (μ) | RA: -20.76 ± 0.56 mas/yr Dec.: 4.30 ± 0.48 mas/yr |
| Parallax (π) | 5.4391 ± 0.4369 mas |
| Distance | 600 ± 50 ly (180 ± 10 pc) |
| Absolute magnitude (MV) | −1.98 |
| Details | |
| Mass | 5.955 M☉ 7.2±0.1 M☉ |
| Radius | 5.00±0.10 R☉ |
| Luminosity | 1,342 L☉ |
| Surface gravity (log g) | 3.20±0.03 cgs |
| Temperature | 20,000±200 K |
| Rotational velocity (v sin i) | 200±4 km/s |
| Age | 31.6±0.6 Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
The stellar classification of the visible component is B3V, matching a B-type main-sequence star. It is around 32 million years old and is spinning rapidly with estimates of its projected rotational velocity ranging from 200 up to 270 km, giving it an equatorial bulge that is up to 11% larger than the polar radius. This is a Be star showing emission features in its Balmer lines due to a circumstellar disk of decreated gas. It is classified as a suspected Gamma Cassiopeiae type variable star with a visual magnitude varying from +4.30 down to +4.39.