Omicron1 Centauri
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Centaurus |
| Right ascension | 11h 31m 46.07s |
| Declination | −59° 26′ 31.4″ |
| Apparent magnitude (V) | +5.13 |
| Characteristics | |
| Evolutionary stage | Yellow hypergiant |
| Spectral type | G3 0-Ia |
| B−V color index | +1.08 |
| Variable type | SRd |
| Astrometry | |
| Radial velocity (Rv) | −20.00 km/s |
| Proper motion (μ) | RA: −4.491 mas/yr Dec.: +1.604 mas/yr |
| Parallax (π) | 0.3254±0.0734 mas |
| Distance | 10,100+2,700 −1,100 ly (3,110+820 −530 pc) |
| Absolute magnitude (MV) | −9.0 |
| Details | |
| Mass | 27±5.4 M☉ |
| Radius | 440±35 R☉ |
| Luminosity | 68,000 L☉ |
| Surface gravity (log g) | 0.19 cgs |
| Temperature | 5,700 K |
| Age | 10–12 Myr |
| Other designations | |
| HR 4441, HD 100261, CD−58°4100, HIP 56243, SAO 239145, GC 15818, CCDM J11318-5927, AAVSO 1127-58 | |
| Database references | |
| SIMBAD | data |
Omicron1 Centauri (ο1 Cen, ο1 Centauri) is a star in the constellation Centaurus. It is approximately 10,000 light years from Earth, though this is very uncertain.
ο1 Centauri is a yellow G-type supergiant or hypergiant with a mean apparent magnitude of +5.13. Daniel Joseph Kelly O'Connell discovered that the star is a variable star by studying photographic plates taken from 1934 to 1952, and announced his discovery in 1961. It is classified as a semiregular variable star and its brightness varies from magnitude +5.8 to +6.6 with a period of 200 days. Other studies have reported only small brightness variations. It is the MK spectral standard for class G3 O-Ia, indicating a highly luminous mass-losing hypergiant star. It has also be classified as F8 Ia0 and F7 Ia/ab. The size, luminosity, and distance are equally uncertain.
ο1 Cen forms a very close naked eye double star with ο2 Centauri, a hotter blue supergiant that may be physically associated. ο1 Cen also has an 11th magnitude companion only 13.5" distant, although it appears to be a foreground star unrelated to the other two. ο1 Cen is located very close to V382 Carinae, the brightest yellow hypergiant star in the night sky.