Astronomy:51 Hydrae

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Short description: Star in the constellation Hydra
51 Hydrae
Observation data
Equinox J2000.0]] (ICRS)
Constellation Hydra
Right ascension  14h 23m 05.77393s[1]
Declination −27° 45′ 14.4609″[1]
Apparent magnitude (V) 4.78[2]
Characteristics
Evolutionary stage giant
Spectral type K4 III[3]
B−V color index 1.300±0.040[2]
Astrometry
Radial velocity (Rv)19.7±0.9[2] km/s
Proper motion (μ) RA: −202.476[1] mas/yr
Dec.: −117.186[1] mas/yr
Parallax (π)19.2042 ± 0.2252[1] mas
Distance170 ± 2 ly
(52.1 ± 0.6 pc)
Absolute magnitude (MV)1.36[2]
Details
Mass1.31[4] M
Radius13.47+0.48
−1.26
[1] R
Luminosity54.9+0.8
−1.5
[1] L
Surface gravity (log g)2.25[5] cgs
Temperature4,255±31[4] K
Metallicity [Fe/H]0.08[5] dex
Other designations
k Hya, 51 Hya, NSV 6648, CD−27°9803, HD 125932, HIP 70306, HR 5381, SAO 182483[6]
Database references
SIMBADdata

51 Hydrae is a single[7] star in the equatorial constellation of Hydra,[6] located 170 light years away from the Sun.[1] It has the Bayer designation k Hydrae; 51 Hydrae is the Flamsteed designation.[6] This object is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 4.78. It is moving further from the Earth with a heliocentric radial velocity of +20 km/s.[2] Eggen (1971) listed it as a member of the η Cephei group of old-disk stars.[8]

This is an evolved giant star with a stellar classification of K4 III,[3] which indicates it has exhausted the supply of hydrogen at its core and expanded off the main sequence. It has 1.31[4] times the mass of the Sun but has swollen to 13.5[1] times the Sun's radius. The star is radiating 55[1] times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,255 K.[4]

References

  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode2018A&A...616A...1G.  Gaia DR2 record for this source at VizieR.
  2. 2.0 2.1 2.2 2.3 2.4 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode2012AstL...38..331A. 
  3. 3.0 3.1 Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins Catalog of Revised MK Types for the Cooler Stars", The Astrophysical Journal Supplement Series 71: 245, doi:10.1086/191373, Bibcode1989ApJS...71..245K. 
  4. 4.0 4.1 4.2 4.3 Luck, R. Earle (2015), "Abundances in the Local Region. I. G and K Giants", Astronomical Journal 150 (3): 88, doi:10.1088/0004-6256/150/3/88, Bibcode2015AJ....150...88L 
  5. 5.0 5.1 McWilliam, Andrew (December 1990), "High-resolution spectroscopic survey of 671 GK giants. I - Stellar atmosphere parameters and abundances", Astrophysical Journal Supplement Series 74: 1075–1128, doi:10.1086/191527, Bibcode1990ApJS...74.1075M. 
  6. 6.0 6.1 6.2 "k Hya". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=k+Hya. 
  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, doi:10.1111/j.1365-2966.2008.13596.x, Bibcode2008MNRAS.389..869E. 
  8. Eggen, O. J. (June 1971), "The ζ Herculis, σ Puppis, ∈ Indi, and η Cephei Groups of Old Disk Population Stars", Publications of the Astronomical Society of the Pacific 83 (493): 251, doi:10.1086/129119, Bibcode1971PASP...83..251E.