71 Cygni

71 Cygni is a star in the northern constellation of Cygnus, located 212 light years from the Sun.[1] 71 Cygni is the Flamsteed designation; it has the Bayer designation g Cygni.[5] It is visible to the naked eye as a dim, orange-hued star with an apparent visual magnitude of 5.22.[2] The star is moving closer to the Earth with a heliocentric radial velocity of −21.5 km/s.[4]

71 Cygni
Observation data
Epoch J2000      Equinox J2000
Constellation Cygnus
Right ascension 21h 29m 26.94995s[1]
Declination +46° 32′ 26.1024″[1]
Apparent magnitude (V) 5.22[2]
Characteristics
Spectral type K0− III[3]
B−V color index 0.965±0.004[2]
Astrometry
Radial velocity (Rv)−21.54±0.10[4] km/s
Proper motion (μ) RA: +43.048[1] mas/yr
Dec.: +104.683[1] mas/yr
Parallax (π)15.4057 ± 0.1077[1] mas
Distance212 ± 1 ly
(64.9 ± 0.5 pc)
Absolute magnitude (MV)1.11[2]
Details[4]
Mass2.05±0.09 M☉
Radius8.31±0.32 R☉
Luminosity44.7+7.8
−6.7 L☉
Surface gravity (log g)3.03±0.05 cgs
Temperature4,983±18 K
Metallicity [Fe/H]0.05±0.06 dex
Rotational velocity (v sin i)2.03±0.85 km/s
Age1.07±0.15 Gyr
Other designations
g Cyg, 71 Cyg, BD+45°3558, FK5 807, HD 204771, HIP 106093, HR 8228, SAO 50934[5]
Database references
SIMBADdata

At the age of one billion years,[4] this is an evolved giant star with a stellar classification of K0− III,[3] which means it has used up its core hydrogen and expanded. It is a red clump giant, indicating that it is on the horizontal branch of the Hertzsprung–Russell diagram and is generating energy by helium fusion at its center.[6][7] The star has double the mass of the Sun and eight times the Sun's radius. It is radiating 45 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,983 K.[4]

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. 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.
  3. Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series, 71: 245, Bibcode:1989ApJS...71..245K, doi:10.1086/191373.
  4. Jofré, E.; et al. (2015), "Stellar parameters and chemical abundances of 223 evolved stars with and without planets", Astronomy & Astrophysics, 574: A50, arXiv:1410.6422, Bibcode:2015A&A...574A..50J, doi:10.1051/0004-6361/201424474, S2CID 53666931.
  5. "71 Cyg". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-01-18.
  6. Mishenina, T. V.; et al. (September 2006), "Elemental abundances in the atmosphere of clump giants", Astronomy and Astrophysics, 456 (3): 1109–1120, arXiv:astro-ph/0605615, Bibcode:2006A&A...456.1109M, doi:10.1051/0004-6361:20065141, S2CID 18764566.
  7. Valentini, M.; Munari, U. (November 2010), "A spectroscopic survey of faint, high-Galactic-latitude red clump stars. I. The high resolution sample", Astronomy and Astrophysics, 522: A79, arXiv:1007.0207, Bibcode:2010A&A...522A..79V, doi:10.1051/0004-6361/201014870, S2CID 119156545.
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