51 Hydrae

This article is about k Hydrae. Not to be confused with κ (kappa) Hydrae.
51 Hydrae
Observation data
Epoch J2000      Equinox J2000
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 mas[1]
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]

  1. ^ a b c d e f g h i j Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  2. ^ a b c d e Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference Keenan1989 was invoked but never defined (see the help page).
  4. ^ a b c d Cite error: The named reference Luck2015 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference McWilliam1990 was invoked but never defined (see the help page).
  6. ^ a b c Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference Eggen1971 was invoked but never defined (see the help page).