Sigma Centauri
Star in the constellation Centaurus
From Wikipedia, the free encyclopedia
Sigma Centauri is a solitary[9] star in the southern constellation of Centaurus. Its name is a Bayer designation that is Latinized from σ Centauri, and abbreviated Sigma Cen or σ Cen. This star is visible to the naked eye with an apparent visual magnitude of 3.91.[3] 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,[10] but its association with Sigma Centauri remains undetermined as of 2013.[11] The distance to Sigma Centauri, based upon an annual parallax shift of 7.92 mas,[2] is around 412 light years.
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Centaurus[1] |
| Right ascension | 12h 28m 02.38208s[2] |
| Declination | −50° 13′ 50.2872″[2] |
| Apparent magnitude (V) | 3.91[3] |
| Characteristics | |
| Evolutionary stage | Main sequence |
| Spectral type | B3 V[4] |
| U−B color index | −0.805[3] |
| B−V color index | −0.202[3] |
| Astrometry | |
| Radial velocity (Rv) | +12.8±1.4[5] km/s |
| Proper motion (μ) | RA: −32.36 mas/yr[2] Dec.: −12.51 mas/yr[2] |
| Parallax (π) | 7.92±0.18 mas[2] |
| Distance | 412 ± 9 ly (126 ± 3 pc) |
| Absolute magnitude (MV) | −1.60[1] |
| Details | |
| Mass | 6.8±0.1[4] M☉ |
| Radius | 4.5[6] R☉ |
| Luminosity | 1,101[7] L☉ |
| Temperature | 15,744[7] K |
| Rotational velocity (v sin i) | 169[5] km/s |
| Age | 25.3±6.3[4] Myr |
| Other designations | |
| σ Cen, CD−49°7115, FK5 464, HD 108483, HIP 60823, HR 4743, SAO 223454[8] | |
| Database references | |
| SIMBAD | data |
This is a B-type main sequence star with a stellar classification of B3 V.[4] It is a helium-rich star, the most massive type of chemically peculiar star.[12] Sigma Centauri has around 6.8 times the mass of the Sun and 4.5 times the Sun's radius.[6] It has a relatively high rate of spin with a projected rotational velocity of 169 km/s,[5] and is around 25 million years old.[4] The star radiates 1,101 times the solar luminosity from its outer atmosphere at an effective temperature of 15,744 K.[7] It is a member of the Lower Centaurus Crux component of the Scorpius–Centaurus association.[5]