Chi1 Hydrae

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For other stars with this Bayer designation, see χ Hydrae
Chi1 Hydrae
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Hydra
Right ascension 11h 05m 19.90766s[1]
Declination −27° 17′ 36.9957″[1]
Apparent magnitude (V) 4.94[2]
Spectral type F4 V + F7 V[3]
U−B color index +0.04[2]
B−V color index +0.36[2]
Radial velocity (Rv) +19.1±1.6[4] km/s
Proper motion (μ) RA: −190.41[1] mas/yr
Dec.: −5.96[1] mas/yr
Parallax (π) 23.13 ± 0.29[1] mas
Distance 141 ± 2 ly
(43.2 ± 0.5 pc)
Absolute magnitude (MV) 1.74[5]
Period (P) 7.5535±0.0064 yr
Semi-major axis (a) 0.1388±0.0016"
Eccentricity (e) 0.349±0.015
Inclination (i) 96.50±0.84°
Longitude of the node (Ω) 224.00±0.59°
Periastron epoch (T) 1983.455 ± 0.084
Argument of periastron (ω)
χ1 Hya A
Mass 1.93[7] M
Metallicity [Fe/H] −0.10[5] dex
Age 1.3[5] Gyr
χ1 Hya B
Mass 1.93[7] M
Other designations
χ1 Hya, CD−26° 8338, FK5 419, GJ 3642, HD 96202, HIP 54204, HR 4314, SAO 179514.[8]
Database references

Chi1 Hydrae (χ1 Hya) is a binary star[3] in the equatorial constellation of Hydra. It originally received the Flamsteed designation of 9 Crateris before being placed in the Hydra constellation.[9] Based upon an annual parallax shift of 23.13 mas as seen from Earth, it is located about 141 light years from the Sun. It is visible to the naked with a combined apparent visual magnitude of 4.94.[2]

The two components of this system appear to have equal masses of 1.93 times the mass of the Sun.[6] The pair circle each other with an orbital period of 7.55 years with an eccentricity of 0.35.[6]


  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 d Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99), Bibcode:1966CoLPL...4...99J. 
  3. ^ a b 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. 
  4. ^ 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. 
  5. ^ a b c Nordström, B.; et al. (May 2004), "The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of ˜14 000 F and G dwarfs", Astronomy and Astrophysics, 418: 989–1019, arXiv:astro-ph/0405198Freely accessible, Bibcode:2004A&A...418..989N, doi:10.1051/0004-6361:20035959. 
  6. ^ a b c Mason, Brian D.; et al. (February 1999), "Binary Star Orbits from Speckle Interferometry. I. Improved Orbital Elements of 22 Visual Systems", The Astronomical Journal, 117 (2): 1023−1036, Bibcode:1999AJ....117.1023M, doi:10.1086/300748. 
  7. ^ a b Jaime, Luisa G.; et al. (December 2012), "Regions of dynamical stability for discs and planets in binary stars of the solar neighbourhood", Monthly Notices of the Royal Astronomical Society, 427 (4): 2723–2733, arXiv:1208.2051Freely accessible, Bibcode:2012MNRAS.427.2723J, doi:10.1111/j.1365-2966.2012.21839.x. 
  8. ^ "chi01 Hya -- Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2017-03-17. 
  9. ^ Wagman, M. (August 1987), "Flamsteed's Missing Stars", Journal for the History of Astronomy, 18: 216, Bibcode:1987JHA....18..209W, doi:10.1177/002182868701800305.