Gamma Mensae

Gamma Mensae, Latinized from γ Mensae, is an orange-hued star system in the southern constellation of Mensa. The apparent visual magnitude of 5.19[2] indicates it is dimly visible to the naked eye. Based upon an annual parallax shift of 7.70 mas as seen from the Earth,[1] it is about 102 light years from the Sun. At that distance, the visual magnitude is diminished by an extinction factor of 0.033 due to interstellar dust.[9] The system shows the high velocity kinematic properties of a population II star, but has Sun-like abundances of most elements.[11]

Gamma Mensae
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Mensa
Right ascension  05h 31m 53.01393s[1]
Declination −76° 20′ 27.4779″[1]
Apparent magnitude (V) 5.19[2]
Characteristics
Spectral type K2 III[3][4]
U−B color index +1.18[2]
B−V color index +1.13[2]
Astrometry
Radial velocity (Rv)+56.7±0.8[5] km/s
Proper motion (μ) RA: +140.646[6] mas/yr
Dec.: +269.634[6] mas/yr
Parallax (π)31.1021 ± 0.1519[6] mas
Distance104.9 ± 0.5 ly
(32.2 ± 0.2 pc)
Absolute magnitude (MV)+2.70[7]
Orbit[8]
Period (P)7.455±4.857 yr
Semi-major axis (a)51±10″
Eccentricity (e)0.59±0.15
Inclination (i)53±8°
Longitude of the node (Ω)117±90°
Periastron epoch (T)1995.111±4.085
Argument of periastron (ω)
(secondary)		124±74°
Details[9]
γ Men A
Mass1.04 M☉
Radius4.99 R☉
Luminosity21 L☉
Surface gravity (log g)2.76[3] cgs
Temperature4,491[3] K
Metallicity [Fe/H]+0.22 dex
Age10.60 Gyr
Other designations
γ Men, CD−76° 222, HD 37763, HIP 25918, HR 1953, SAO 256201[10]
Database references
SIMBADdata

This is a probable astrometric binary system[4] with poorly constrained orbital elements. The visible member, component A, is an evolved K-type giant star with a stellar classification K2 III[3] At about 10.6 billion years of age, it has nearly the same mass as the Sun but has expanded to five times the Sun's radius.[9] The star shines with 21 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,491 K.[3]

References
  1. 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.
  2. Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99), Bibcode:1966CoLPL...4...99J.
  3. Gray, R. O.; et al. (July 2006), "Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample", The Astronomical Journal, 132 (1): 161–170, arXiv:astro-ph/0603770, Bibcode:2006AJ....132..161G, doi:10.1086/504637.
  4. 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.
  5. de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, A61.
  6. 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.
  7. 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.
  8. Hartkopf, W. I.; et al. (June 30, 2006), Sixth Catalog of Orbits of Visual Binary Stars, United States Naval Observatory, retrieved 2017-06-02.
  9. Wittenmyer, Robert A.; Liu, Fan; Wang, Liang; Casagrande, Luca; Johnson, John Asher; Tinney, C. G. (July 2016), "The Pan-Pacific Planet Search. V. Fundamental Parameters for 164 Evolved Stars", The Astronomical Journal, 152 (1): 15, arXiv:1605.00323, Bibcode:2016AJ....152...19W, doi:10.3847/0004-6256/152/1/19, 19.
  10. "gam Men". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-08-16.
  11. Foy, R. (May 1980), "Detailed analysis of high velocity stars", Astronomy and Astrophysics, 85 (3): 287–294, Bibcode:1980A&A....85..287F.
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