Gamma Sextantis

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γ Sextantis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Sextans
Right ascension 09h 52m 30.43727s[1]
Declination −08° 06′ 18.1269″[1]
Apparent magnitude (V) 5.05[2] (5.6 + 6.0)[3]
Spectral type A0/1 V[4] (A1 V + A4 V)[5]

color index


color index

Radial velocity (Rv) +12[6] km/s
Proper motion (μ) RA: −57.28[1] mas/yr
Dec.: −49.26[1] mas/yr
Parallax (π) 11.75 ± 0.63[1] mas
Distance 280 ± 10 ly
(85 ± 5 pc)
Period (P) 77.55 yr
Semi-major axis (a) 0.383″
Eccentricity (e) 0.691
Inclination (i) 145.1°
Longitude of the node (Ω) 31.0°
Argument of periastron (ω)
Mass 2.60[7] M
Luminosity 57[8] L
Surface gravity (log g) 4.18±0.14[7] cgs
Temperature 9,825±334[7] K
Rotational velocity (v sin i) 134.6±1.4[9] km/s
Age 401[7] Myr
Other designations
γ Sex, 8 Sextantis, BD−07° 2909, HD 85558, HIP 48437, HR 3909, SAO 137199.[10]
Database references

Gamma Sextantis (γ Sex, γ Sextantis) is a binary star[11] system in the equatorial constellation of Sextans. The combined apparent visual magnitude of the system is 5.05,[2] which means it is faintly visible to the naked eye. The annual parallax shift is 11.75 mas,[1] indicating a distance of around 280 light years.

The two components orbit each other with a period of 77.55 years and a high eccentricity of 0.691. The orbital plane is inclined by 145.1° to the line of sight from the Earth.[1] With a visual magnitude of 5.6,[5] the brighter component A is an A-type main sequence star with a stellar classification of A1 V.[5] The fainter companion B has a classification of A4 V[5] with a magnitude of 6.0.[5] Their combined spectral matches a classification of A0/1 V.[4]

There is a magnitude 12.28 companion star C at an angular separation of 36.9 arc seconds along a position angle of 333°, as of 2000. This separation has increased from 30.0 arc seconds in 1834. The proper motion of this star differs from the Gamma Sextantis AB system, having components μα = −29 mas/yr and μδ = +5 mas/yr.[12]


  1. ^ a b c d e f g van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752Freely accessible, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d 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. ^ a b Heintz, W. D. (March 1982), "Orbits of 16 visual binaries", Astronomy and Astrophysics Supplement Series, 47: 569–573, Bibcode:1982A&AS...47..569H. 
  4. ^ a b Houk, N.; Swift, C. (1999), "Michigan catalogue of two-dimensional spectral types for the HD Stars", Michigan Spectral Survey, Ann Arbor, Michigan: Department of Astronomy, University of Michigan, 5, Bibcode:1999MSS...C05....0H. 
  5. ^ a b c d e Edwards, T. W. (April 1976), "MK classification for visual binary components", Astronomical Journal, 81: 245–249, Bibcode:1976AJ.....81..245E, doi:10.1086/111879. 
  6. ^ Wilson, Ralph Elmer (1953), General Catalogue of Stellar Radial Velocities, Washington: Carnegie Institution of Washington, Bibcode:1953GCRV..C......0W. 
  7. ^ a b c d David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154Freely accessible, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146. 
  8. ^ 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:1208.2037Freely accessible, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x. 
  9. ^ Díaz, C. G.; et al. (July 2011), "Accurate stellar rotational velocities using the Fourier transform of the cross correlation maximum", Astronomy & Astrophysics, 531: A143, arXiv:1012.4858Freely accessible, Bibcode:2011A&A...531A.143D, doi:10.1051/0004-6361/201016386. 
  10. ^ "gam Sex – Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2016-12-14. 
  11. ^ Eggleton, P. P.; et al. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878Freely accessible, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x. 
  12. ^ Mason, B. D.; et al. (2014), The Washington Visual Double Star Catalog, Bibcode:2001AJ....122.3466M, doi:10.1086/323920.