2 Sextantis

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2 Sextantis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Hydra
Right ascension  09h 38m 27.28962s[1]
Declination +04° 38′ 57.4461″[1]
Apparent magnitude (V) 4.68[2]
Evolutionary stage giant
Spectral type K3 III[2]
B−V color index +1.310±0.033[3]
Radial velocity (Rv)+44.61±0.23[4] km/s
Proper motion (μ) RA: −163.18[1] mas/yr
Dec.: −50.88[1] mas/yr
Parallax (π)11.04 ± 0.27[1] mas
Distance295 ± 7 ly
(91 ± 2 pc)
Absolute magnitude (MV)−0.10[3]
Mass1.32[2] M
Radius24[4] R
Luminosity190.5[2] L
Surface gravity (log g)2.09±0.22[5] cgs
Temperature4,188±33[2] K
Metallicity [Fe/H]−0.30±0.09[5] dex
Rotational velocity (v sin i)3.0[4] km/s
Age4.58[2] Gyr
Other designations
2 Sex, BD+05° 2207, FK5 1249, HD 83425, HIP 47310, HR 3834, SAO 117821[6]
Database references

2 Sextantis is a single[7] star that is now in the equatorial constellation Hydra, located around 295 light years away from the Sun. It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 4.68.[2] This object is moving further from the Earth with a heliocentric radial velocity of +44.6 km/s.[4] It has a relatively high proper motion, traversing the celestial sphere at the rate of 0.173 per year.[8]

This is a giant star with a stellar classification of K3 III,[2] which, at the age of 4.58[2] billion years old, has exhausted the hydrogen at its core and evolved away from the main sequence. The star has 1.32[2] times the mass of the Sun and has expanded to 24[4] times the Sun's radius. It is radiating 190.5[2] times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,188 K.[2]


  1. ^ a b c d e Van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357.
  2. ^ a b c d e f g h i j k l Luck, R. Earle (2015), "Abundances in the Local Region. I. G and K Giants", The Astronomical Journal, 150 (3): 88, arXiv:1507.01466, Bibcode:2015AJ....150...88L, doi:10.1088/0004-6256/150/3/88.
  3. ^ a b 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.
  4. ^ a b c d e Massarotti, Alessandro; et al. (January 2008), "Rotational and Radial Velocities for a Sample of 761 Hipparcos Giants and the Role of Binarity", The Astronomical Journal, 135 (1): 209–231, Bibcode:2008AJ....135..209M, doi:10.1088/0004-6256/135/1/209.
  5. ^ a b Prugniel, Ph.; et al. (July 2011), "The atmospheric parameters and spectral interpolator for the MILES stars", Astronomy & Astrophysics, 531: A165, arXiv:1104.4952, Bibcode:2011A&A...531A.165P, doi:10.1051/0004-6361/201116769.
  6. ^ "2 Sex". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-04-08.
  7. ^ 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.
  8. ^ Lépine, Sébastien; Shara, Michael M. (March 2005), "A Catalog of Northern Stars with Annual Proper Motions Larger than 0.15" (LSPM-NORTH Catalog)", The Astronomical Journal, 129 (3): 1483–1522, arXiv:astro-ph/0412070, Bibcode:2005AJ....129.1483L, doi:10.1086/427854.