Sigma Centauri
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.
| 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 mas[1] |
| 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 | |
| Database references | |
| SIMBAD | data |
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
- ^ a b c d e f 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.
- ^ 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.
- ^ 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, arXiv:1007.4883, Bibcode:2011MNRAS.410..190T, doi:10.1111/j.1365-2966.2010.17434.x, S2CID 118629873.
- ^ 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, arXiv:astro-ph/0601643, Bibcode:2006A&A...448.1001J, doi:10.1051/0004-6361:20041614, S2CID 17818058.
- ^ 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, S2CID 119257644.
- ^ 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, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451, S2CID 425754.
- ^ 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, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x, S2CID 118665352.
- ^ "sig Cen". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-01-12.
- ^ 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.
- ^ 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.
- ^ 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.
- ^ 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.