HD 79940

HD 79940 is a single[9] star in the southern constellation of Vela. It has the Bayer designation of k Velorum; HD 79940 is the identifier from the Henry Draper Catalogue. This star has a yellow-white hue and is faintly visible to the naked eye as a point light source with an apparent visual magnitude of 4.63.[2] It is located at a distance of approximately 158 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +6 km/s.[2]

This article is about k Velorum. It is not to be confused with κ (Kappa) Velorum.
HD 79940
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Vela
Right ascension 09h 15m 45.07943s[1]
Declination −37° 24′ 47.3124″[1]
Apparent magnitude (V) 4.63[2]
Characteristics
Spectral type F3/5V[3] or F5III[4][5]
B−V color index 0.473±0.002[2]
Astrometry
Radial velocity (Rv)+5.8±2.8[2] km/s
Proper motion (μ) RA: +14.128[1] mas/yr
Dec.: −8.111[1] mas/yr
Parallax (π)20.5985 ± 0.1895[1] mas
Distance158 ± 1 ly
(48.5 ± 0.4 pc)
Absolute magnitude (MV)1.12[2]
Details[6]
Mass1.36[6] M☉
Radius4.35+0.11
−0.19[1] R☉
Luminosity28.427±0.305[1] L☉
Surface gravity (log g)3.26±0.14[6] cgs
Temperature6,388+143
−76[1] K
Metallicity [Fe/H]0.20±0.15[2] dex
Rotational velocity (v sin i)117.2±5.9[7] km/s
Age2.76[6] Gyr
Other designations
k Vel, CD−36 5505, GJ 339.3, GJ 9293, HD 79940, HIP 45448, HR 3684, SAO 200163, WDS J09158-3725A[8]
Database references
SIMBADdata

There has been some disagreement over the stellar classification of this star. In 1975, S. Maladora found a class of F5III, suggesting an evolved F-type star,[4] matching an earlier (1957) classification by A. de Vaucouleurs.[5] N. Houk assigned it a class of F3/5V in 1979, matching an F-type main-sequence star.[3] It has a high rate of spin with a projected rotational velocity of 117.2±5.9 km/s.[7] This may explain why it was incorrectly classified as a spectroscopic binary in 1972.[9]

There is a faint magnitude 14.50 companion at an angular separation of 11.3″ along a position angle of 126° from the brighter star. This was discovered by T. J. J. See in 1897.[10]

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. Houk, Nancy (1979), Michigan catalogue of two-dimensional spectral types for the HD stars, 3, Ann Arbor, Michigan: Department of Astronomy, University of Michigan, Bibcode:1982mcts.book.....H.
  4. Malaroda, S. (August 1975), "Study of the F-type stars. I. MK spectral types.", Astronomical Journal, 80: 637–641, Bibcode:1975AJ.....80..637M, doi:10.1086/111786.
  5. de Vaucouleurs, A. (1957). "Spectral types and luminosities of B, A and F southern stars". Monthly Notices of the Royal Astronomical Society. 117 (4): 449. Bibcode:1957MNRAS.117..449D. doi:10.1093/mnras/117.4.449.
  6. 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:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, S2CID 33401607.
  7. Reiners, A. (January 2006), "Rotation- and temperature-dependence of stellar latitudinal differential rotation", Astronomy and Astrophysics, 446 (1): 267–277, arXiv:astro-ph/0509399, Bibcode:2006A&A...446..267R, doi:10.1051/0004-6361:20053911.
  8. "HD 79940". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-09-28.
  9. Kunzli, M.; North, P. (January 1998), "Are metallic A-F giants evolved AM stars? Rotation and rate of binaries among giant F stars", Astronomy and Astrophysics Supplement, 127: 277–294, arXiv:astro-ph/9710226, Bibcode:1998A&AS..127..277K, doi:10.1051/aas:1998350.
  10. Mason, B. D.; et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal, 122 (6): 3466–3471, Bibcode:2001AJ....122.3466M, doi:10.1086/323920.
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