Sigma Centauri
Sigma Centauri, Latinized from σ Centauri, is the Bayer designation for a solitary star in the southern constellation of Centaurus. It is visible to the naked eye with an apparent visual magnitude of 3.91. A visual companion at an angular separation of 88.11±0.37 mas along a position angle of 14.33°±2.59° was detected in 2010 using interferometry, but its association with Sigma Centauri remains undetermined as of 2013. The distance to Sigma Centauri, based upon an annual parallax shift of 7.92 mas, is around 412 light years.
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Centaurus |
| Right ascension | 12h 28m 02.38208s |
| Declination | −50° 13′ 50.2872″ |
| Apparent magnitude (V) | 3.91 |
| Characteristics | |
| Spectral type | B3 V |
| U−B color index | −0.805 |
| B−V color index | −0.202 |
| Astrometry | |
| Radial velocity (Rv) | +12.8±1.4 km/s |
| Proper motion (μ) | RA: −32.36 mas/yr Dec.: −12.51 mas/yr |
| Parallax (π) | 7.92 ± 0.18 mas |
| Distance | 412 ± 9 ly (126 ± 3 pc) |
| Absolute magnitude (MV) | −1.60 |
| Details | |
| Mass | 6.8±0.1 M☉ |
| Radius | 4.5 R☉ |
| Luminosity | 1,101 L☉ |
| Temperature | 15,744 K |
| Rotational velocity (v sin i) | 169 km/s |
| Age | 25.3±6.3 Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
This is a B-type main sequence star with a stellar classification of B3 V. It is a helium-rich star, the most massive type of chemically peculiar star. Sigma Centauri has around 6.8 times the mass of the Sun and 4.5 times the Sun's radius. It has a relatively high rate of spin with a projected rotational velocity of 169 km/s, and is around 25 million years old. The star radiates 1,101 times the solar luminosity from its outer atmosphere at an effective temperature of 15,744 K. It is a member of the Lower Centaurus Crux component of the Scorpius–Centaurus association.