Article · Wikipedia archive · Last revised Jun 20, 2026

Sigma Centauri

Sigma Centauri is a solitary star in the southern constellation of Centaurus. Its name is a Bayer designation that is Latinized from σ Centauri, and abbreviated Sigma Cen or σ Cen. This star is visible to the naked eye with an apparent visual magnitude of 3.91. A visual companion at an angular separation of 88.11±0.37 mas along a position angle of 14.33°±2.59° was detected in 2010 using interferometry, but its association with Sigma Centauri remains undetermined as of 2013. The distance to Sigma Centauri, based upon an annual parallax shift of 7.92 mas, is around 412 light years.

Last revised
Jun 20, 2026
Read time
≈ 3 min
Length
600 w
Citations
31
Source
Wikipedia ↗
σ Centauri
Location of σ Centauri (circled in red)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Centaurus1
Right ascension 12h 28m 02.38208s2
Declination −50° 13′ 50.2872″2
Apparent magnitude (V) 3.913
Characteristics
Evolutionary stage Main sequence
Spectral type B3 V4
U−B color index −0.8053
B−V color index −0.2023
Astrometry
Radial velocity (Rv)+12.8±1.45 km/s
Proper motion (μ) RA: −32.36 mas/yr2
Dec.: −12.51 mas/yr2
Parallax (π)7.92±0.18 mas2
Distance412 ± 9 ly
(126 ± 3 pc)
Absolute magnitude (MV)−1.601
Details
Mass6.8±0.14 M☉
Radius4.56 R☉
Luminosity1,1017 L☉
Temperature15,7447 K
Rotational velocity (v sin i)1695 km/s
Age25.3±6.34 Myr
Other designations
σ Cen, CD−49°7115, FK5 464, HD 108483, HIP 60823, HR 4743, SAO 2234548
Database references
SIMBADdata

Sigma Centauri is a solitary9 star in the southern constellation of Centaurus. Its name is a Bayer designation that is Latinized from σ Centauri, and abbreviated Sigma Cen or σ Cen. This star is visible to the naked eye with an apparent visual magnitude of 3.91.3 A visual companion at an angular separation of 88.11±0.37 mas along a position angle of 14.33°±2.59° was detected in 2010 using interferometry,10 but its association with Sigma Centauri remains undetermined as of 2013.11 The distance to Sigma Centauri, based upon an annual parallax shift of 7.92 mas,2 is around 412 light years.

This is a B-type main sequence star with a stellar classification of B3 V.4 It is a helium-rich star, the most massive type of chemically peculiar star.12 Sigma Centauri has around 6.8 times the mass of the Sun and 4.5 times the Sun's radius.6 It has a relatively high rate of spin with a projected rotational velocity of 169 km/s,5 and is around 25 million years old.4 The star radiates 1,101 times the solar luminosity from its outer atmosphere at an effective temperature of 15,744 K.7 It is a member of the Lower Centaurus Crux component of the Scorpius–Centaurus association.5

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. (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. Gutierrez-Moreno, Adelina; Moreno, Hugo (June 1968), "A photometric investigation of the Scorpio-Centaurus association", Astrophysical Journal Supplement, 15: 459, Bibcode:1968ApJS...15..459G, doi:10.1086/190168.
  4. 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.
  5. Jilinski, E.; et al. (March 2006), "Radial velocity measurements of B stars in the Scorpius–Centaurus association", Astronomy and Astrophysics, 448 (3): 1001–1006, arXiv:astro-ph/0601643, Bibcode:2006A&A...448.1001J, doi:10.1051/0004-6361:20041614, S2CID 17818058.
  6. Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics, 367 (3rd ed.): 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451, S2CID 425754.
  7. McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x, S2CID 118665352.
  8. "sig Cen", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2017-01-12
  9. Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
  10. Rizzuto, A. C.; et al. (December 2013), "Long-baseline interferometric multiplicity survey of the Sco-Cen OB association", Monthly Notices of the Royal Astronomical Society, 436 (2): 1694–1707, arXiv:1309.3811, Bibcode:2013MNRAS.436.1694R, doi:10.1093/mnras/stt1690.
  11. Gullikson, Kevin; Dodson-Robinson, Sarah (January 2013), "Detection of Low-Mass-ratio Stellar Binary Systems", The Astronomical Journal, 145 (1): 13, arXiv:1210.6360, Bibcode:2013AJ....145....3G, doi:10.1088/0004-6256/145/1/3, S2CID 118517725, 3.
  12. Zboril, M.; North, P. (May 1999), "Properties of He-rich stars. II. CNO abundances and projected rotational velocities", Astronomy and Astrophysics, 345: 244–248, Bibcode:1999A&A...345..244Z.