HD 85859

HD 85859

Observation data Epoch J2000      Equinox J2000
Constellation	Hydra[1]
Right ascension	09^h 54^m 12.32596^s[2]
Declination	−25° 55′ 56.3631″[2]
Apparent magnitude (V)	4.88[3]
Characteristics
Evolutionary stage	red clump[4]
Spectral type	K2+ III CN0.5[5]
B−V color index	1.23[3]
Astrometry
Radial velocity (Rv)	50.5[3] km/s
Proper motion (μ)	RA: −187.764[2] mas/yr Dec.: +52.746[2] mas/yr
Parallax (π)	12.5809±0.2161 mas[2]
Distance	259 ± 4 ly (79 ± 1 pc)
Absolute magnitude (MV)	−0.23[1]
Details
Mass	1.55[3] M☉
Luminosity	178[3] L☉
Surface gravity (log g)	2.35[6] cgs
Temperature	4,415±25[3] K
Metallicity [Fe/H]	−0.03[6] dex
Age	4.34[3] Gyr
Other designations
CD−25°7585, FK5 2792, HD 85859, HIP 48559, HR 3919, SAO 178158[7]
Database references
SIMBAD	data

HD 85859 is a single^[8] star in the equatorial constellation of Hydra. It has an apparent visual magnitude of 4.88,^[3] 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,^[2] is 259 light years. It is moving away from the Earth with a heliocentric radial velocity of 50.5 km/s.^[3]

The stellar classification of the visible component is K2+ III CN0.5,^[5] which matches an evolved K-type giant star with a mild overabundance of CN in the atmosphere. At the age of 4.34^[3] 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.^[4] The star has 1.55^[3] times the mass of the Sun and is radiating 178^[3] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,415 K.^[3]

References

1. 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.
2. 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.
3. 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. S2CID 118505114.
4. 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, S2CID 16673121.
5. 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
6. 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, S2CID 118362423.
7. "HD 85859". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-07-26.
8. 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, S2CID 14878976.