Xi Hydrae

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Xi Hydrae
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Hydra
Right ascension 11h 33m 00.11505s[1]
Declination −31° 51′ 27.4435″[1]
Apparent magnitude (V) 3.54[2]
Spectral type G7 III[2]
Radial velocity (Rv) −4.90±0.30[3] km/s
Proper motion (μ) RA: −209.62[1] mas/yr
Dec.: −40.84[1] mas/yr
Parallax (π) 25.16 ± 0.16[1] mas
Distance 129.6 ± 0.8 ly
(39.7 ± 0.3 pc)
Mass 2.94±0.15[4] M
Radius 10.2±0.1[5] R
Luminosity 57.65±2.39[5] L
Surface gravity (log g) 2.87±0.02[4] cgs
Temperature 5,044±40[4] K
Metallicity [Fe/H] +0.16±0.20[4] dex
Rotational velocity (v sin i) 2.7[5] km/s
Other designations
ξ Lyr, 288 G. Hydrae, CD−31° 9083, HD 100407, HIP 56343, HR 4450, SAO 202558.[6]
Database references

Xi Hydrae (ξ Hya, ξ Hydrae) is a solitary[7] star in the equatorial constellation of Hydra. It received the Flamsteed designation 19 Crateris prior to joining the Hydra constellation.[8] This magnitude 3.54[2] star is situated 130 light-years from Earth and has a radius about 10 times that of the Sun. It is radiating 58 times as much luminosity as the Sun.[5] The star is now approaching the end of its life, and has expanded its outer envelope to become a red giant star.

One possible non-radial oscillation mode of Xi Hydrae

The star Xi Hya was particularly interesting in the field of asteroseismology when an international group of astronomers discovered that it behaves like a giant sub-ultra-bass musical instrument.[9]


  1. ^ a b c d e van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752Freely accessible, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c Mallik, Sushma V. (December 1999), "Lithium abundance and mass", Astronomy and Astrophysics, 352: 495–507, Bibcode:1999A&A...352..495M. 
  3. ^ de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048Freely accessible, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, A61. 
  4. ^ a b c d Heiter, U.; Jofré, P.; Gustafsson, B.; Korn, A. J.; Soubiran, C.; Thévenin, F. (2015), "Gaia FGK benchmark stars: Effective temperatures and surface gravities", Astronomy & Astrophysics, 582: A49, arXiv:1506.06095Freely accessible, Bibcode:2015A&A...582A..49H, doi:10.1051/0004-6361/201526319. 
  5. ^ a b c d Bruntt, H.; et al. (July 2010), "Accurate fundamental parameters for 23 bright solar-type stars", Monthly Notices of the Royal Astronomical Society, 405 (3): 1907–1923, arXiv:1002.4268Freely accessible, Bibcode:2010MNRAS.405.1907B, doi:10.1111/j.1365-2966.2010.16575.x. 
  6. ^ "ksi Hya -- Double or multiple star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2017-03-22. 
  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, arXiv:0806.2878Freely accessible, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x. 
  8. ^ Wagman, M. (August 1987), "Flamsteed's Missing Stars", Journal for the History of Astronomy, 18: 216, Bibcode:1987JHA....18..209W, doi:10.1177/002182868701800305. 
  9. ^ West, Richard (May 15, 2002), "Ultrabass Sounds of the Giant Star xi Hya: First Observations of Solar-type Oscillations in a Star Very Different from the Sun", Innovations Report, retrieved 2017-03-23. 

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