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

ο² Centauri

Location of ο2 Cen (circled)
Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Centaurus
Right ascension	11h 31m 48.79948s[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 mas[1]
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