# Chi1 Hydrae

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Star in the constellation Hydra

For other stars with this [Bayer designation](/source/Bayer_designation), see [χ Hydrae](/source/Chi_Hydrae)

Chi1 Hydrae Location of χ1 Hydrae (circled in red) Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) Constellation Hydra[1] Right ascension 11h 05m 19.90766s[2] Declination −27° 17′ 36.9957″[2] Apparent magnitude (V) 4.94[3] Characteristics Spectral type F4 V + F7 V[4] U−B color index +0.04[3] B−V color index +0.36[3] Astrometry Radial velocity (Rv) +19.1±1.6[5] km/s Proper motion (μ) RA: −190.728[6] mas/yr Dec.: −6.273[6] mas/yr Parallax (π) 22.8323±0.1828 mas[6] Distance 143 ± 1 ly (43.8 ± 0.4 pc) Absolute magnitude (MV) 1.74[7] Orbit[8] 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) (secondary) 343.0±4.3° Details χ1 Hya A Mass 1.93[9] M☉ Radius 3.19[6] R☉ Luminosity 17.798[6] L☉ Temperature 6,637[6] K Metallicity [Fe/H] −0.10[7] dex Age 1.3[7] Gyr χ1 Hya B Mass 1.93[9] M☉ Other designations χ1 Hya, CD−26°8338, FK5 419, GJ 3642, HD 96202, HIP 54204, HR 4314, SAO 179514[10] Database references SIMBAD data

**Chi1 Hydrae** (**χ1 Hydrae**) is a [binary star](/source/Binary_star)[4] in the equatorial [constellation](/source/Constellation) of [Hydra](/source/Hydra_(constellation)). It originally received the [Flamsteed designation](/source/Flamsteed_designation) of **9 Crateris** before being placed in the Hydra constellation.[11] Based upon an annual [parallax shift](/source/Stellar_parallax) of 22.8 [mas](/source/Milliarcsecond) as seen from Earth, it is located about 143 [light years](/source/Light_year) from the [Sun](/source/Sun). It is visible to the naked eye with a combined [apparent visual magnitude](/source/Apparent_visual_magnitude) of 4.94.[3]

The two components of this system appear to have equal masses of 1.93 times the [mass of the Sun](/source/Solar_mass).[8] The pair circle each other with an [orbital period](/source/Orbital_period) of 7.55 years with an [eccentricity](/source/Orbital_eccentricity) of 0.35.[8]

## References

1. **[^](#cite_ref-constellation_1-0)** [Roman, Nancy G.](/source/Nancy_Roman) (1987), ["Identification of a constellation from a position"](https://doi.org/10.1086%2F132034), *[Publications of the Astronomical Society of the Pacific](/source/Publications_of_the_Astronomical_Society_of_the_Pacific)*, **99** (617): 695, [Bibcode](/source/Bibcode_(identifier)):[1987PASP...99..695R](https://ui.adsabs.harvard.edu/abs/1987PASP...99..695R), [doi](/source/Doi_(identifier)):[10.1086/132034](https://doi.org/10.1086%2F132034). [Constellation record for this object](https://vizier.cds.unistra.fr/viz-bin/VizieR-4?source=VI%2F42%2Fout&%2F%2Ftables=VI%2F42%2Fout&-c=9+Crt&-c.eq=J2000&-c.r=++2&-c.u=arcmin&-c.geom=r&-source=&-source=VI%2F42%2Fout&-out=RA1875&-out=DE1875&-out=Cst) at [VizieR](/source/VizieR).

1. ^ [***a***](#cite_ref-vanLeeuwen2007_2-0) [***b***](#cite_ref-vanLeeuwen2007_2-1) van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", *Astronomy and Astrophysics*, **474** (2): 653–664, [arXiv](/source/ArXiv_(identifier)):[0708.1752](https://arxiv.org/abs/0708.1752), [Bibcode](/source/Bibcode_(identifier)):[2007A&A...474..653V](https://ui.adsabs.harvard.edu/abs/2007A&A...474..653V), [doi](/source/Doi_(identifier)):[10.1051/0004-6361:20078357](https://doi.org/10.1051%2F0004-6361%3A20078357), [S2CID](/source/S2CID_(identifier)) [18759600](https://api.semanticscholar.org/CorpusID:18759600).

1. ^ [***a***](#cite_ref-Johnson1966_3-0) [***b***](#cite_ref-Johnson1966_3-1) [***c***](#cite_ref-Johnson1966_3-2) [***d***](#cite_ref-Johnson1966_3-3) Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", *Communications of the Lunar and Planetary Laboratory*, **4** (99): 99, [Bibcode](/source/Bibcode_(identifier)):[1966CoLPL...4...99J](https://ui.adsabs.harvard.edu/abs/1966CoLPL...4...99J).

1. ^ [***a***](#cite_ref-Eggleton2008_4-0) [***b***](#cite_ref-Eggleton2008_4-1) Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", *[Monthly Notices of the Royal Astronomical Society](/source/Monthly_Notices_of_the_Royal_Astronomical_Society)*, **389** (2): 869–879, [arXiv](/source/ArXiv_(identifier)):[0806.2878](https://arxiv.org/abs/0806.2878), [Bibcode](/source/Bibcode_(identifier)):[2008MNRAS.389..869E](https://ui.adsabs.harvard.edu/abs/2008MNRAS.389..869E), [doi](/source/Doi_(identifier)):[10.1111/j.1365-2966.2008.13596.x](https://doi.org/10.1111%2Fj.1365-2966.2008.13596.x), [S2CID](/source/S2CID_(identifier)) [14878976](https://api.semanticscholar.org/CorpusID:14878976).

1. **[^](#cite_ref-deBruijne2012_5-0)** 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](/source/ArXiv_(identifier)):[1208.3048](https://arxiv.org/abs/1208.3048), [Bibcode](/source/Bibcode_(identifier)):[2012A&A...546A..61D](https://ui.adsabs.harvard.edu/abs/2012A&A...546A..61D), [doi](/source/Doi_(identifier)):[10.1051/0004-6361/201219219](https://doi.org/10.1051%2F0004-6361%2F201219219), [S2CID](/source/S2CID_(identifier)) [59451347](https://api.semanticscholar.org/CorpusID:59451347), A61.

1. ^ [***a***](#cite_ref-dr2_6-0) [***b***](#cite_ref-dr2_6-1) [***c***](#cite_ref-dr2_6-2) [***d***](#cite_ref-dr2_6-3) [***e***](#cite_ref-dr2_6-4) [***f***](#cite_ref-dr2_6-5) [Brown, A. G. A.](/source/Anthony_Brown_(scientist)); et al. ([Gaia collaboration](/source/Data_Processing_and_Analysis_Consortium)) (August 2018). ["*Gaia* Data Release 2: Summary of the contents and survey properties"](https://doi.org/10.1051%2F0004-6361%2F201833051). *[Astronomy & Astrophysics](/source/Astronomy_%26_Astrophysics)*. **616**. A1. [arXiv](/source/ArXiv_(identifier)):[1804.09365](https://arxiv.org/abs/1804.09365). [Bibcode](/source/Bibcode_(identifier)):[2018A&A...616A...1G](https://ui.adsabs.harvard.edu/abs/2018A&A...616A...1G). [doi](/source/Doi_(identifier)):[10.1051/0004-6361/201833051](https://doi.org/10.1051%2F0004-6361%2F201833051). [Gaia DR2 record for this source](https://vizier.u-strasbg.fr/viz-bin/VizieR-S?Gaia%20DR2%203532314252513733888) at [VizieR](/source/VizieR).

1. ^ [***a***](#cite_ref-Nordstroem2004_7-0) [***b***](#cite_ref-Nordstroem2004_7-1) [***c***](#cite_ref-Nordstroem2004_7-2) 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](/source/ArXiv_(identifier)):[astro-ph/0405198](https://arxiv.org/abs/astro-ph/0405198), [Bibcode](/source/Bibcode_(identifier)):[2004A&A...418..989N](https://ui.adsabs.harvard.edu/abs/2004A&A...418..989N), [doi](/source/Doi_(identifier)):[10.1051/0004-6361:20035959](https://doi.org/10.1051%2F0004-6361%3A20035959), [S2CID](/source/S2CID_(identifier)) [11027621](https://api.semanticscholar.org/CorpusID:11027621).

1. ^ [***a***](#cite_ref-Mason1999_8-0) [***b***](#cite_ref-Mason1999_8-1) [***c***](#cite_ref-Mason1999_8-2) 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](/source/Bibcode_(identifier)):[1999AJ....117.1023M](https://ui.adsabs.harvard.edu/abs/1999AJ....117.1023M), [doi](/source/Doi_(identifier)):[10.1086/300748](https://doi.org/10.1086%2F300748).

1. ^ [***a***](#cite_ref-Jaime2012_9-0) [***b***](#cite_ref-Jaime2012_9-1) 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](/source/ArXiv_(identifier)):[1208.2051](https://arxiv.org/abs/1208.2051), [Bibcode](/source/Bibcode_(identifier)):[2012MNRAS.427.2723J](https://ui.adsabs.harvard.edu/abs/2012MNRAS.427.2723J), [doi](/source/Doi_(identifier)):[10.1111/j.1365-2966.2012.21839.x](https://doi.org/10.1111%2Fj.1365-2966.2012.21839.x), [S2CID](/source/S2CID_(identifier)) [118570249](https://api.semanticscholar.org/CorpusID:118570249).

1. **[^](#cite_ref-SIMBAD_10-0)** ["chi01 Hya"](http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=chi01+Hya), *[SIMBAD](/source/SIMBAD)*, [Centre de données astronomiques de Strasbourg](/source/Centre_de_donn%C3%A9es_astronomiques_de_Strasbourg), retrieved 2017-03-17.

1. **[^](#cite_ref-Wagman1987_11-0)** Wagman, M. (August 1987), "Flamsteed's Missing Stars", *Journal for the History of Astronomy*, **18** (3): 216, [Bibcode](/source/Bibcode_(identifier)):[1987JHA....18..209W](https://ui.adsabs.harvard.edu/abs/1987JHA....18..209W), [doi](/source/Doi_(identifier)):[10.1177/002182868701800305](https://doi.org/10.1177%2F002182868701800305), [S2CID](/source/S2CID_(identifier)) [118445625](https://api.semanticscholar.org/CorpusID:118445625).

v t e Constellation of Hydra List of stars in Hydra Hydra in Chinese astronomy Stars Bayer α (Alphard) β γ (Naga) δ ε (Ashlesha) ζ η θ ι (Ukdah) κ λ μ ν ξ ο π ρ σ (Minchir) τ1 τ2 υ1 (Zhang) υ2 φ1 φ2 φ3 χ1 χ2 ψ ω b1 b3 C F Flamsteed 1 2 3 6 (a) 9 10 12 (D) 14 15 17 19 20 21 23 24 25 26 27 (P) 28 29 33 (A) 34 37 44 47 48 50 51 (k) 52 (l) 54 (m) 55 56 57 58 (Solitaire) 59 60 10 Crt 17 Crt 20 Crt 2 Sex Variable R U V W TW EX HS KU LQ V361 V419 V421 V478 V484 HR 3378 3538 3749 (G) 3750 3858 (I) 3862 3919 3923 (Felis) 4162 4328 4339 (β Ant) 4445 5265 HD 72659 74156 82943 86226 86264 90156 (γ Ant) Other 2MASS 1114−2618 ESO 439-26 Gliese 328 Gliese 357 Gliese 433 Gliese 453 GJ 3634 HAT-P-30 HE 1256−2738 HE 1327−2326 LHS 2065 LHS 3003 LTT 3780 SDSS J090745.0+024507 WASP-25 WASP-36 WASP-84 WASP-166 (Filetdor) WISE 0855−0714 WISEA J1141−3326 Exoplanets Gliese 357 d HD 72659 b HD 74156 b c HD 82943 b c HD 86226 b HD 86264 b TW Hydrae b (unconfirmed) WASP-193b Star clusters Messier 48 Messier 68 NGC 5694 Price-Whelan 1 Nebulae Abell 33 Abell 35 NGC 3242 Southern Owl Nebula Galaxies Messier 83 NGC 2617 2642 2697 2708 2758 2835 2848 2865 2890 2935 2936 2937 2960 2962 2986 2992 3030 3052 3054 3081 3109 3124 3200 3285 3285B 3290 3305 3307 3308 3309 3311 3312 3313 3314 3315 3316 3336 3369 3383 3393 3402 3463 3464 3585 3621 3673 3717 3904 3923 3936 4980 4993 5042 5061 5078 5085 5101 5135 5260 5264 5495 5626 Other 3C 196.1 AM 1316−241 Arp 7 CTQ 327 ESO 510-G13 GAMA202627 GLEAM J0917−0012 Hydra A IC 535 MRC 1138−262 Peekaboo Galaxy PKS 1151−348 RX J0911.4+0551 SDSS J0841+0101 TN J0924−2201 Tololo 1247−232 ZwCl 1693 BCG Galaxy clusters Abell 754 Abell 3411 Abell 3412 Bullet Group Hickson 40 Astronomical events GW170817 Category

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Adapted from the Wikipedia article [Chi1 Hydrae](https://en.wikipedia.org/wiki/Chi1_Hydrae) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Chi1_Hydrae?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.