Omicron1 Centauri
Star in the constellation Centaurus
From Wikipedia, the free encyclopedia
Omicron1 Centauri is a yellow hypergiant star in the southern constellation of Centaurus. Its name is a Bayer designation that is Latinized from ο1 Centauri, and abbreviated Omicron1 Cen or ο1 Cen. It is approximately 9,400 light-years from Earth.
  | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Centaurus |
| Right ascension | 11h 31m 46.07s[1] |
| Declination | −59° 26′ 31.4″[1] |
| Apparent magnitude (V) | +5.13[2] |
| Characteristics | |
| Evolutionary stage | Yellow hypergiant |
| Spectral type | G3_0-Ia[3] |
| B−V color index | +1.08[2] |
| Variable type | SRd[4] |
| Astrometry | |
| Radial velocity (Rv) | −20.00[5] km/s |
| Proper motion (μ) | RA: −4.491 mas/yr[1] Dec.: +1.604 mas/yr[1] |
| Parallax (π) | 0.3254±0.0734 mas[1] |
| Distance | 9,390 ± 330 ly (2,880±100 pc)[6] |
| Absolute magnitude (MV) | −9.0[7] |
| Details | |
| Mass | 27±5.4[8] M☉ |
| Radius | 403±41[6] R☉ |
| Luminosity | 210,000+88,000 −82,000[6] L☉ |
| Surface gravity (log g) | 0.19[9] cgs |
| Temperature | 5,700[10] K |
| Age | 10–12[10] Myr |
| Other designations | |
| ο1 Cen, AAVSO 1127-58, CD−58°4100, GC 15818, HD 100261, HIP 56243, HR 4441, SAO 239145, CCDM J11318-5927[11] | |
| Database references | |
| SIMBAD | data |
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.[13] 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.[4] Other studies have reported only small brightness variations.[14][15] It has been assigned the spectral types F8 Ia0[16] and F7 Ia/ab,[17] indicating an F-type hypergiant or F-type supergiant respectively, but this has been revised to G3_0 Ia in 1989, indicating that it is a G-type hypergiant,[3] and has been listed as the spectral standard for this class.[18] The star is around 400 times larger than the Sun and roughly 210,000 times more luminous.[6]
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,[19] although it appears to be a foreground star unrelated to the other two.[20]
