Epsilon Centauri

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ε Centauri
Centaurus constellation map.svg
Red circle.svg

Location of δ Orionis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Centaurus
Right ascension 13h 39m 53.25774s[1]
Declination −53° 27′ 59.0081″[1]
Apparent magnitude (V) +2.30[2] (2.29 - 2.31[3])
Spectral type B1 III[4]
U−B color index −0.92[2]
B−V color index −0.22[2]
Variable type β Cep[3]
Radial velocity (Rv) +3.0[5] km/s
Proper motion (μ) RA: −15.30[1] mas/yr
Dec.: −11.72[1] mas/yr
Parallax (π) 7.63 ± 0.48[1] mas
Distance 430 ± 30 ly
(131 ± 8 pc)
Absolute magnitude (MV) –3.9[6]
Mass 11.60 ± 1.06[4] M
Luminosity 15,217[4] L
Surface gravity (log g) 3.68[6] cgs
Temperature 24,000[4] K
Metallicity [Fe/H] –0.14 ± 0.10[7] dex
Rotational velocity (v sin i) 160[8] km/s
Age 15.8 ± 5.7[9] Myr
Other designations
CP−52 6655, FK5 504, HD 118716, HIP 66657, HR 5132, SAO 241047.
Database references

Epsilon Centauri (ε Cen, ε Centauri) is a star in the southern constellation of Centaurus. It 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.[10] Consequently, ε Centauri itself is known as 南門一 (Nán Mén yī, English: the First Star of Southern Gate.)[11]

ε Centauri is a massive star with nearly 12 times the mass of the Sun.[4] The spectrum matches a stellar classification of B1 III,[4] indicating this is an evolved giant star. It is radiating more than 15,000[4] times the luminosity of the Sun from its outer atmosphere at an effective temperature of 24,000 K,[4] giving it the blue-white hue of a B-type star.[12] This 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.[7] 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.[6] Epsilon Centauri is a relatively young star, with an age of around 16 million years.[9]


  1. ^ a b c d e 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 
  2. ^ a b c 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. 
  3. ^ a b 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. ^ a b c d e f g h Hohle, M. M.; Neuhäuser, R.; Schutz, B. F. (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 
  5. ^ Evans, D. S. (June 20–24, 1966), Batten, Alan Henry; Heard, John Frederick, eds., The Revision of the General Catalogue of Radial Velocities, University of Toronto: International Astronomical Union, Bibcode:1967IAUS...30...57E 
  6. ^ a b c de Geus, E. J.; de Zeeuw, P. T.; Lub, J. (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 
  7. ^ a b 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 
  8. ^ Balona, L. A.; Dziembowski, W. A. (October 1999), "Excitation and visibility of high-degree modes in stars", Monthly Notices of the Royal Astronomical Society 309 (1): 221–232, Bibcode:1999MNRAS.309..221B, doi:10.1046/j.1365-8711.1999.02821.x 
  9. ^ a b Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (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 
  10. ^ (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.
  11. ^ (Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 25 日
  12. ^ "The Colour of Stars", Australia Telescope, Outreach and Education (Commonwealth Scientific and Industrial Research Organisation), December 21, 2004, retrieved 2012-01-16