Article · Wikipedia archive · Last revised Jun 7, 2026

Epsilon Centauri

Epsilon Centauri is a star in the southern constellation of Centaurus. Its name is a Bayer designation that is Latinized from ε Centauri, and abbreviated Epsilon Cen or ε Cen. This is one of the brightest stars in the constellation with a slightly variable apparent visual magnitude of +2.30. Parallax measurements put it at a distance of around 430 light-years from Earth.

Last revised
Jun 7, 2026
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Wikipedia ↗
ε Centauri
Location of ε Centauri (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Centaurus1
Right ascension 13h 39m 53.25774s2
Declination −53° 27′ 59.0081″2
Apparent magnitude (V) 2.29 - 2.313
Characteristics
Spectral type B1 III4
U−B color index −0.925
B−V color index −0.225
Variable type β Cep3
Astrometry
Radial velocity (Rv)+3.06 km/s
Proper motion (μ) RA: −15.302 mas/yr
Dec.: −11.722 mas/yr
Parallax (π)7.63±0.48 mas2
Distance430 ± 30 ly
(131 ± 8 pc)
Absolute magnitude (MV)−3.291
Details
Mass8.27 M☉
Radius5.88 R☉
Luminosity16,1378 L☉
Surface gravity (log g)3.888 cgs
Temperature24,9378 K
Metallicity [Fe/H]−0.14±0.109 dex
Rotational velocity (v sin i)14010 km/s
Age16.311 Myr
Other designations
ε Cen, CPD−52°6655, FK5 504, HD 118716, HIP 66657, HR 5132, SAO 24104712
Database references
SIMBADdata

Epsilon Centauri is a star in the southern constellation of Centaurus. Its name is a Bayer designation that is Latinized from ε Centauri, and abbreviated Epsilon Cen or ε Cen. This is one of the brightest stars in the constellation with a slightly variable apparent visual magnitude of +2.30. Parallax measurements put it at a distance of around 430 light-years (130 parsecs) from Earth.

In Chinese, 南門 (Nán Mén), meaning Southern Gate, refers to an asterism consisting of ε Centauri and α Centauri.13 Consequently, the Chinese name for ε Centauri itself is 南門一 (Nán Mén yī, English: the First Star of Southern Gate.)14

A yellow-light light curve for Epsilon Centauri, adapted from Shobbrook (1972)15 source ↗

ε Centauri is a massive star with 8.2 times the mass of the Sun.7 The spectrum matches a stellar classification of B1 III,4 indicating this is an evolved giant star. It is radiating more than 16,000 times the luminosity of the Sun8 from its outer atmosphere at an effective temperature of about 25,000 K,8 giving it the blue-white hue of a B-type star.16 It is classified as a Beta Cephei type variable star with a primary period of 0.16961 days (4 hours 4 minutes), completing 5.9 cycles per day.9 During each cycle, the brightness of the star varies from apparent magnitude +2.29 to +2.31.

This star is a proper motion member of the Lower Centaurus–Crux sub-group in the Scorpius–Centaurus OB association, the nearest such association of co-moving massive stars to the Sun.17 Epsilon Centauri is a relatively young star, with an age of around 16 million years.18

The IAU has not assigned a proper name to this star.19

References

References

  1. Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. XHIP record for this object at VizieR.
  2. van Leeuwen, F. (November 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. S2CID 18759600.
  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: 02025. Bibcode:2009yCat....102025S.
  4. Hohle, M. M.; et al. (April 2010). "Masses and luminosities of O- and B-type stars and red supergiants". Astronomische Nachrichten. 331 (4): 349. arXiv:1003.2335. Bibcode:2010AN....331..349H. doi:10.1002/asna.200911355. S2CID 111387483.
  5. 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: 0. Bibcode:2002yCat.2237....0D.
  6. Evans, D. S. (June 20–24, 1966). "The Revision of the General Catalogue of Radial Velocities". In Batten, Alan Henry; Heard, John Frederick (eds.). Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30. Vol. 30. University of Toronto: International Astronomical Union. p. 57. Bibcode:1967IAUS...30...57E.
  7. Quintana, Alexis L.; Wright, Nicholas J.; Martínez García, Juan (2025). "A census of OB stars within 1 KPC and the star formation and core collapse supernova rates of the Milky Way". Monthly Notices of the Royal Astronomical Society. 538 (3): 1367. arXiv:2503.08286. Bibcode:2025MNRAS.538.1367Q. doi:10.1093/mnras/staf083.
  8. McDonald, I.; Zijlstra, A. A.; Watson, R. A. (2017). "Fundamental parameters and infrared excesses of Tycho-Gaia stars". Monthly Notices of the Royal Astronomical Society. 471 (1): 770. arXiv:1706.02208. Bibcode:2017MNRAS.471..770M. doi:10.1093/mnras/stx1433.
  9. Daszyńska-Daszkiewicz, J.; Niemczura, E. (April 2005). "Metallicity of mono- and multiperiodic β Cephei stars". Astronomy and Astrophysics. 433 (3): 1031–1035. arXiv:astro-ph/0410442. Bibcode:2005A&A...433.1031D. doi:10.1051/0004-6361:20040397. S2CID 119340011.
  10. Van Belle, Gerard T. (2012). "Interferometric observations of rapidly rotating stars". Astronomy and Astrophysics Review. 20 (1) 51. arXiv:1204.2572. Bibcode:2012A&ARv..20...51V. doi:10.1007/s00159-012-0051-2.
  11. Gratton, R.; Squicciarini, V.; Nascimbeni, V.; Janson, M.; Reffert, S.; Meyer, M.; Delorme, P.; Mamajek, E. E.; Bonavita, M.; Desidera, S.; Mesa, D.; Rigliaco, E.; d'Orazi, V.; Vigan, A.; Lazzoni, C.; Chauvin, G.; Langlois, M. (2023). "Multiples among B stars in the Scorpius-Centaurus association". Astronomy and Astrophysics. 678: A93. arXiv:2308.09962. Bibcode:2023A&A...678A..93G. doi:10.1051/0004-6361/202346806.
  12. "Eps Cen". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2025-12-08.
  13. (in Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
  14. (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 25 日 Archived 2011-05-22 at the Wayback Machine
  15. Shobbrook, R. R. (1972). "Two new Beta Canis Majoris variables: epsilon Cen and delta Lup". Monthly Notices of the Royal Astronomical Society. 157. Bibcode:1972MNRAS.157P...5S. doi:10.1093/mnras/157.1.5P.
  16. "The Colour of Stars". Australia Telescope, Outreach and Education. Commonwealth Scientific and Industrial Research Organisation. December 21, 2004. Archived from the original on 2012-03-18. Retrieved 2012-01-16.
  17. de Geus, E. J.; et al. (June 1989). "Physical parameters of stars in the Scorpio-Centaurus OB association". Astronomy and Astrophysics. 216 (1–2): 44–61. Bibcode:1989A&A...216...44D.
  18. Tetzlaff, N.; et al. (January 2011). "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun". Monthly Notices of the Royal Astronomical Society. 410 (1): 190–200. arXiv:1007.4883. Bibcode:2011MNRAS.410..190T. doi:10.1111/j.1365-2966.2010.17434.x. S2CID 118629873.
  19. "Naming Stars". International Astronomical Union. Archived from the original on 2025-03-10. Retrieved 2023-09-14.