HD 85859

HD 85859 is a single[7] star in the equatorial constellation of Hydra. It has an apparent visual magnitude of 4.88,[2] which is bright enough to be visible to the naked eye. The distance to this star, as estimated from its annual parallax shift of 12.6 mas,[1] is 259 light years. It is moving closer to the Earth with a heliocentric radial velocity of 50.5 km/s.[2]

HD 85859
Observation data
Epoch J2000      Equinox J2000
Constellation Hydra
Right ascension  09h 54m 12.32596s[1]
Declination −25° 55′ 56.3631″[1]
Apparent magnitude (V) 4.88[2]
Characteristics
Spectral type K2+ III CN0.5[3]
B−V color index 1.23[2]
Astrometry
Radial velocity (Rv)50.5[2] km/s
Proper motion (μ) RA: −187.764[1] mas/yr
Dec.: +52.746[1] mas/yr
Parallax (π)12.5809 ± 0.2161[1] mas
Distance259 ± 4 ly
(79 ± 1 pc)
Absolute magnitude (MV)−0.23[4]
Details
Mass1.55[2] M☉
Luminosity178[2] L☉
Surface gravity (log g)2.35[5] cgs
Temperature4,415±25[2] K
Metallicity [Fe/H]−0.03[5] dex
Age4.34[2] Gyr
Other designations
CD−25° 7585, FK5 2792, HD 85859, HIP 48559, HR 3919, SAO 178158[6]
Database references
SIMBADdata

The stellar classification of the visible component is K2+ III CN0.5,[3] which matches an evolved K-type giant star with a mild overabundance of CN in the atmosphere. At the age of 4.34[2] billion years, it is a red clump star, which indicates it is on the horizontal branch and is generating energy through helium fusion at its core.[8] The star has 1.55[2] times the mass of the Sun and is radiating 178[2] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,415 K.[2]

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.
  2. Luck, R. Earle (2015). "Abundances in the Local Region. I. G and K Giants". Astronomical Journal. 150 (3). 88. arXiv:1507.01466. Bibcode:2015AJ....150...88L. doi:10.1088/0004-6256/150/3/88.
  3. Keenan, P.; McNeil, R. (October 1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series, 71: 245–266, Bibcode:1989ApJS...71..245K, doi:10.1086/191373
  4. 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.
  5. Soubiran, C.; et al. (June 2010), "The PASTEL catalogue of stellar parameters", Astronomy and Astrophysics, 515: A111, arXiv:1004.1069, Bibcode:2010A&A...515A.111S, doi:10.1051/0004-6361/201014247.
  6. "HD 85859". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-07-26.
  7. Eggleton, P. P.; Tokovinin, A. A. (2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x.
  8. Alves, David R. (August 2000), "K-Band Calibration of the Red Clump Luminosity", The Astrophysical Journal, 539 (2): 732–741, arXiv:astro-ph/0003329, Bibcode:2000ApJ...539..732A, doi:10.1086/309278.
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