# Omicron2 Centauri

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Variable star in the constellation Centaurus

For other star systems with this [Bayer designation](/source/Bayer_designation), see [Omicron Centauri](/source/Omicron_Centauri).

ο2 Centauri Location of ο2 Cen (circled) Observation data Epoch J2000.0 Equinox J2000.0 Constellation Centaurus Right ascension 11h 31m 48.79955s[1] Declination −59° 30′ 56.3296″[1] Apparent magnitude (V) +5.14[2] (5.12 - 5.22[3]) Characteristics Evolutionary stage Blue supergiant Spectral type A2Iae[3] 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: −6.976 mas/yr[1] Dec.: +1.118 mas/yr[1] Parallax (π) 0.4665±0.0713 mas[1] Distance approx. 7,000 ly (approx. 2,100 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 ο2 Cen, CD−58°4101, FK5 2920, GC 15820, HD 100262, HIP 56250, HR 4442, SAO 239146[6] Database references SIMBAD data

**Omicron2 Centauri** is a [star](/source/Star) in the southern [constellation](/source/Constellation) [Centaurus](/source/Centaurus). Its name is a [Bayer designation](/source/Bayer_designation) that is [Latinied](/source/Romanization_of_Greek) from ο2 Centauri, and abbreviated Omicron2 Cen or ο2 Cen. This star is visible to the [naked eye](/source/Naked_eye) with a mean [apparent visual magnitude](/source/Apparent_visual_magnitude) of +5.12. Based on [parallax](/source/Stellar_parallax) measurements, it is located at a distance of approximately 7,000 [light years](/source/Light_years) from [Earth](/source/Earth).

ο2 Centauri is a white [A-type](/source/Stellar_classification) [blue supergiant](/source/Blue_supergiant). It is classified as an [Alpha Cygni type](/source/Alpha_Cygni_variable) [variable star](/source/Variable_star) and its brightness varies from magnitude +5.12 to +5.22 with a [period](/source/Frequency) 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](/source/Omicron1_Centauri), another 5th magnitude [supergiant](/source/Supergiant) (possibly a [yellow hypergiant](/source/Yellow_hypergiant)). Both stars are located between [Crux](/source/Crux) (the Southern Cross) and the brightest yellow hypergiant in the sky, [V382 Carinae](/source/V382_Carinae).

## References

1. ^ [***a***](#cite_ref-dr3_1-0) [***b***](#cite_ref-dr3_1-1) [***c***](#cite_ref-dr3_1-2) [***d***](#cite_ref-dr3_1-3) Vallenari, A.; et al. (Gaia collaboration) (2023). ["*Gaia* Data Release 3. Summary of the content and survey properties"](https://doi.org/10.1051%2F0004-6361%2F202243940). *Astronomy and Astrophysics*. **674**: A1. [arXiv](/source/ArXiv_(identifier)):[2208.00211](https://arxiv.org/abs/2208.00211). [Bibcode](/source/Bibcode_(identifier)):[2023A&A...674A...1G](https://ui.adsabs.harvard.edu/abs/2023A&A...674A...1G). [doi](/source/Doi_(identifier)):[10.1051/0004-6361/202243940](https://doi.org/10.1051%2F0004-6361%2F202243940). [S2CID](/source/S2CID_(identifier)) [244398875](https://api.semanticscholar.org/CorpusID:244398875). [Gaia DR3 record for this source](https://vizier.cds.unistra.fr/viz-bin/VizieR-4?-source=+I%2F355&-from=nav&-nav=cat%3AI%2F355%26tab%3A%7BI%2F355%2Fgaiadr3%7D%26key%3Asource%3D1355%2Fgaiadr3%26HTTPPRM%3A%26-out.add%3D.%26Source%3D%3D%3D5336114548828274560%26-go+%25%23Sesame%23%25%26) at [VizieR](/source/VizieR).

1. ^ [***a***](#cite_ref-ducati_2-0) [***b***](#cite_ref-ducati_2-1) [***c***](#cite_ref-ducati_2-2) 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](/source/Bibcode_(identifier)):[2002yCat.2237....0D](https://ui.adsabs.harvard.edu/abs/2002yCat.2237....0D).

1. ^ [***a***](#cite_ref-gcvs_3-0) [***b***](#cite_ref-gcvs_3-1) [***c***](#cite_ref-gcvs_3-2) 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](/source/Bibcode_(identifier)):[2009yCat....102025S](https://ui.adsabs.harvard.edu/abs/2009yCat....102025S).

1. **[^](#cite_ref-Wilson_1953_4-0)** Wilson, Ralph Elmer (1953). *General catalogue of stellar radial velocities*. Carnegie Institution of Washington. [Bibcode](/source/Bibcode_(identifier)):[1953GCRV..C......0W](https://ui.adsabs.harvard.edu/abs/1953GCRV..C......0W).

1. ^ [***a***](#cite_ref-Kaufer_1996_5-0) [***b***](#cite_ref-Kaufer_1996_5-1) [***c***](#cite_ref-Kaufer_1996_5-2) Kaufer, A.; et al. (1996). "Long-term spectroscopic monitoring of BA-type supergiants. I. Halpha_ line-profile variability". *Astronomy and Astrophysics*. **305**: 887–901. [Bibcode](/source/Bibcode_(identifier)):[1996A&A...305..887K](https://ui.adsabs.harvard.edu/abs/1996A&A...305..887K).

1. **[^](#cite_ref-SIMBAD_6-0)** ["omi02 Cen"](http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=omi02+Cen). *[SIMBAD](/source/SIMBAD)*. [Centre de données astronomiques de Strasbourg](/source/Centre_de_donn%C3%A9es_astronomiques_de_Strasbourg). Retrieved 2025-12-24.

v t e Constellation of Centaurus List of stars in Centaurus Centaurus in Chinese astronomy Stars Bayer α A (Rigil Kentaurus) B (Toliman) C (Proxima Centauri) β (Hadar) γ δ ε ζ (Leepwal) η θ (Menkent) ι (Kulou) κ λ μ ν (Heng) ξ1 ξ2 ο1 ο2 π ρ σ τ υ1 υ2 φ χ ψ x1 x2 C3 D E F G H J K M N Q Flamsteed 1 (i) 2 (g) 3 (k) 4 (h) Variable R T V Y RR SV SX BV DY UY V346 V553 V744 V752 V761 (a) V763 (C1) V766 V779 (Krzemiński's star) V803 V810 V816 (Przybylski's Star) V831 V842 V885 V886 V863 V1032 V1369 V1400 V1935 HR 4460 (A) 4466 (C2) 4499 4522 4523 4537 (j) 4546 (B) 4721 4748 (u) 4796 4817 (l) 4831 (w) 4874 (p) 4888 (e) 4889 (n) 4940 (f) 4979 4989 5006 (r) 5041 (m) 5089 (d) 5174 (z) 5222 (y) 5224 5241 5297 5358 (v) 5371 5471 (b) 5485 (c1) 5489 (c2) HD 97413 98176 100453 101581 101930 102117 (Uklun) 103197 107914 108236 109749 110113 113538 113766 114386 114729 115600 116434 (Matza) 117207 117618 (Dofida) 117939 120411 121228 121504 124448 (Popper's Star) 125072 125595 131399 Other 2MASS J1126−5003 2M1207 Gaia BH2 HD 131399 Ab PSR B1259−63 PSR J1311−3430 TOI-763 WASP-15 (Nyamien) WASP-41 WASP-42 WASP-167/KELT-13 Exoplanets 2M1207b b Centauri b HD 101930 b HD 102117 b (Leklsullun) HD 103197 b HD 109749 b HD 113538 b c HD 114386 b HD 114729 b HD 117207 b HD 117618 b (Noifasui) HD 121504 b HIP 65426 b (Najsakopajk) HIP 67522 b NGTS-13b Proxima Centauri b c d WASP-15b (Asye) Star clusters NGC 3766 4230 4507 5281 5286 5316 5460 5617 5662 Other IC 2944 ω Centauri Scorpius–Centaurus association Stock 16 Nebulae NGC 3918 5307 Other Boomerang Nebula Fleming 1 G292.0+1.8 G306.3-0.9 Gum 41 IC 2944 IRAS 13208−6020 RCW 79 RCW 86 Southern Crab Nebula SuWt 2 Galaxies NGC 3557 3568 3749 3783 4444 4603 4622 4650A 4683 4696 4706 4709 4729 4730 4743 4744 4909 4930 4945 4976 5011 A 5026 5064 5082 5090 5091 5102 5114 5121 5128 (Centaurus A) 5161 5206 5253 5266 5291 5398 5408 5419 5483 5516 Other ESO 269-57 ESO 325-4 ESO 383-76 ESO 444-46 Fourcade-Figueroa Object IC 3370 IC 4214 IC 4329A IRAS 13224−3809 J1144−4308 LEDA 677373 PKS 1144−379 PKS 1353−341 PKS 1424−418 Galaxy clusters Abell S740 Centaurus Cluster Shapley Supercluster Astronomical events GW190521 SN 185 SN 1895B (Z) SN 1972E SN 1986G J1407b SN 2019so Category

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Adapted from the Wikipedia article [Omicron2 Centauri](https://en.wikipedia.org/wiki/Omicron2_Centauri) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Omicron2_Centauri?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.