Omicron² Centauri

Omicron² Centauri (ο² Cen, ο² Centauri) is a star in the constellation Centaurus.

For other star systems with this Bayer designation, see Omicron Centauri.

ο² Centauri

Location of ο^2 Cen (circled)
Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Centaurus
Right ascension	11^h 31^m 48.79948^s[1]
Declination	−59° 30′ 56.3276″[1]
Apparent magnitude (V)	+5.14[2] (5.12 - 5.22[3])
Characteristics
Spectral type	A2Iae
U−B color index	−0.11[2]
B−V color index	+0.49[2]
Variable type	α Cyg[3]
Astrometry
Radial velocity (Rv)	−16.8[4] km/s
Proper motion (μ)	RA: -6.89 ± 0.26[1] mas/yr Dec.: 1.12 ± 0.24[1] mas/yr
Parallax (π)	0.61 ± 0.28[1] mas
Distance	approx. 5,000 ly (approx. 1,600 pc)
Absolute magnitude (MV)	−7.50[5]
Details[5]
Mass	18 M☉
Radius	131 R☉
Luminosity	105,000 L☉
Surface gravity (log g)	1.46 cgs
Temperature	9,080 K
Rotation	132 days
Rotational velocity (v sin i)	50 km/s
Other designations
HR 4442, HD 100262, CD−58°4101, FK5 2920, HIP 56250, SAO 239146, GC 15820
Database references
SIMBAD	data

ο² Centauri is a white A-type supergiant with a mean apparent magnitude of +5.12. It is approximately 5000 light years from Earth. It is classified as an Alpha Cygni type variable star and its brightness varies from magnitude +5.12 to +5.22 with a period of 46.3 days.

In 1996, Kaufer and colleagues calculated Omicron² Centauri to be around 136,000 times as luminous, 18 times as massive and have 131 times the diameter of the Sun.[5]

ο² Cen forms a close naked eye pair with ο¹ Cen, another 5th magnitude supergiant.

References

1. van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. Vizier catalog entry
2. Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
3. Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/gcvs. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
4. Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Washington. Bibcode:1953GCRV..C......0W.
5. Kaufer, A.; Stahl, O.; Wolf, B.; Gaeng, T.; Gummersbach, C. A.; Kovacs, J.; Mandel, H.; Szeifert, T. (1996). "Long-term spectroscopic monitoring of BA-type supergiants. I. Halpha_ line-profile variability". Astronomy and Astrophysics. 305: 887–901. Bibcode:1996A&A...305..887K.