Sigma Capricorni

Sigma Capricorni, Latinized from σ Capricorni, is a solitary[8] star in the southern constellation of Capricornus,[7] 0.5 degree north of the ecliptic. It is visible to the naked eye as a dim, orange-hued star with an apparent visual magnitude of +5.31.[2] The star is about 1,070 light years away from the Sun based on parallax, but is drifting closer with a radial velocity of −9.6 km/s.[1]

Sigma Capricorni
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Capricornus
Right ascension 20h 19m 23.60402s[1]
Declination −19° 07′ 06.6967″[1]
Apparent magnitude (V) +5.31[2]
Characteristics
Spectral type K2 III[3]
U−B color index +1.56[2]
B−V color index +1.43[2]
Astrometry
Radial velocity (Rv)−9.64±0.16[1] km/s
Proper motion (μ) RA: +8.07[4] mas/yr
Dec.: −11.31[4] mas/yr
Parallax (π)3.0609 ± 0.1194[1] mas
Distance1,070 ± 40 ly
(330 ± 10 pc)
Absolute magnitude (MV)−2.38[5]
Details
Mass6.3±0.7[6] M☉
Radius67.5+4.2
−6.0[1] R☉
Luminosity1,392±64[1] L☉
Temperature4292+204
−127[1] K
Age60.5±17.2[6] Myr
Other designations
σ Cap, CD−19°5776, FK5 3625, HD 193150, HIP 100195, HR 7761, SAO 163445, WDS J20194-1907A[7]
Database references
SIMBADdata

This object is an evolved, K-type giant star with a stellar classification of K2 III.[3] Having exhausted the supply of hydrogen at its core, it has expanded and now has around 67.5[1] times the girth of the Sun. The star is about 60.5[6] million years old with 6.3[6] times the mass of the Sun. It is radiating 1,392[1] times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,292 K.[1]

A magnitude 9.43 visual companion is at an angular separation of 55.90″ along a position angle of 179°, as of 2016.[9]

References
  1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. Fernie, J. D. (May 1983), "New UBVRI photometry for 900 supergiants", Astrophysical Journal Supplement Series, 52: 7–22, Bibcode:1983ApJS...52....7F, doi:10.1086/190856.
  3. Houk, N.; Smith-Moore, M. (1988), Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars, 4, Bibcode:1988mcts.book.....H.
  4. 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.
  5. 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.
  6. 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.
  7. "* sig Cap". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-05-12.
  8. 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.
  9. Mason, B. D.; et al. (2014), The Washington Visual Double Star Catalog, Bibcode:2001AJ....122.3466M, doi:10.1086/323920
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