Sigma Centauri

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σ Centauri
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Centaurus
Right ascension 12h 28m 02.38208s[1]
Declination −50° 13′ 50.2872″[1]
Apparent magnitude (V) 3.91[2]
Characteristics
Spectral type B3 V[3]
U−B color index −0.805[2]
B−V color index −0.202[2]
Astrometry
Radial velocity (Rv) +12.8±1.4[4] km/s
Proper motion (μ) RA: −32.36[1] mas/yr
Dec.: −12.51[1] mas/yr
Parallax (π) 7.92 ± 0.18[1] mas
Distance 412 ± 9 ly
(126 ± 3 pc)
Absolute magnitude (MV) −1.60[5]
Details
Mass 6.8±0.1[3] M
Radius 4.5[6] R
Luminosity 1,101[7] L
Temperature 15,744[7] K
Rotational velocity (v sin i) 169[4] km/s
Age 25.3±6.3[3] Myr
Other designations
σ Cen, CD−49° 7115, FK5 464, HD 108483, HIP 60823, HR 4743, SAO 223454.[8]
Database references
SIMBAD data

Sigma Centauri, Latinized from σ Centauri, is the Bayer designation for a solitary[9] star in the southern constellation of Centaurus. It is visible to the naked eye with an apparent visual magnitude of 3.91.[2] 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,[1] is around 412 light years.

This is a B-type main sequence star with a stellar classification of B3 V.[3] 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[6] times the Sun's radius. It has a relatively high rate of spin with a projected rotational velocity of 169[4] km/s, and is around 25 million years old.[3] The star radiates 1,101 times the solar luminosity from its outer atmosphere at an effective temperature of 15,744[7] K. It is a member of the Lower Centaurus Crux component of the Scorpius–Centaurus Association.[4]

References[edit]

  1. ^ a b c d e f van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, Bibcode:2007A&A...474..653V, arXiv:0708.1752Freely accessible, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d 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. 
  3. ^ a b c d e 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, Bibcode:2011MNRAS.410..190T, arXiv:1007.4883Freely accessible, doi:10.1111/j.1365-2966.2010.17434.x. 
  4. ^ a b c d Jilinski, E.; et al. (March 2006), "Radial velocity measurements of B stars in the Scorpius-Centaurus association", Astronomy and Astrophysics, 448 (3): 1001–1006, Bibcode:2006A&A...448.1001J, arXiv:astro-ph/0601643Freely accessible, doi:10.1051/0004-6361:20041614. 
  5. ^ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, Bibcode:2012AstL...38..331A, arXiv:1108.4971Freely accessible, doi:10.1134/S1063773712050015. 
  6. ^ a b Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics (3rd ed.), 367: 521–524, Bibcode:2001A&A...367..521P, arXiv:astro-ph/0012289Freely accessible, doi:10.1051/0004-6361:20000451. 
  7. ^ a b c McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, Bibcode:2012MNRAS.427..343M, arXiv:1208.2037Freely accessible, doi:10.1111/j.1365-2966.2012.21873.x. 
  8. ^ "sig Cen -- Double or multiple star", SIMBAD Astronomical Database, 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, Bibcode:2008MNRAS.389..869E, arXiv:0806.2878Freely accessible, doi:10.1111/j.1365-2966.2008.13596.x. 
  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, Bibcode:2013MNRAS.436.1694R, arXiv:1309.3811Freely accessible, 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, Bibcode:2013AJ....145....3G, arXiv:1210.6360Freely accessible, doi:10.1088/0004-6256/145/1/3, 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.