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Chi2 Hydrae

From Wikipedia, the free encyclopedia
Binary star system in the constellation Hydra
For other stars with thisBayer designation, seeχ Hydrae
Chi2 Hydrae

Alight curve for Chi2 Hydrae, plotted fromTESS data[1]
Observation data
EpochJ2000.0      EquinoxJ2000.0 (ICRS)
ConstellationHydra
Right ascension11h 05m 57.57000s[2]
Declination−27° 17′ 16.2727″[2]
Apparent magnitude (V)5.65 - 5.94[3](5.85 + 7.57)[4]
Characteristics
Spectral typeB8 III-IVe + B8.5 V[5]
U−Bcolor index−0.26[6]
B−Vcolor index−0.06[6]
Variable typeAlgol (detached)[3]
Astrometry
Radial velocity (Rv)+30.6±0.9[7] km/s
Proper motion (μ)RA: +34.417[2]mas/yr
Dec.: −16.477[2]mas/yr
Parallax (π)4.7616±0.0652 mas[2]
Distance685 ± 9 ly
(210 ± 3 pc)
Orbit[8]
Period (P)2.2677 d
Eccentricity (e)0.00
Periastronepoch (T)2439925.545 JD
Argument of periastron (ω)
(secondary)		0.00°
Semi-amplitude (K1)
(primary)		123.3 km/s
Semi-amplitude (K2)
(secondary)		168.9 km/s
Details[9]
χ Hya A
Mass3.605±0.078 M☉
Radius4.391±0.039 R☉
Luminosity344[10] L☉
Surface gravity (log g)3.65[11] cgs
Temperature11,750±190 K
Rotational velocity (v sin i)112±10[4] km/s
Age158[4] Myr
χ Hya B
Mass2.632±0.049 M☉
Radius2.160±0.030 R☉
Luminosity66[10] L☉
Surface gravity (log g)4.23[4] cgs
Temperature11,100±230 K
Rotational velocity (v sin i)60±6[4] km/s
Other designations
χ Hya,CD−26°8342,HD 96314,HIP 54255,HR 4317,SAO 179522[12]
Database references
SIMBADdata

Chi2 Hydrae, Latinised from χ2 Hydrae, is abinary star system in the equatorialconstellation ofHydra. Based upon an annualparallax shift of 4.6 mas as seen from Earth, it is located roughly 685 light years from theSun. It is visible to the naked eye with a combinedapparent visual magnitude of about 5.7.

This is adetachedeclipsing binary star system with anorbital period of 2.27 days and an essentially circular orbit having a measuredeccentricity of 0.00.[8] The eclipse of the primary by the secondary component reduces the visual magnitude of the system by 0.29, while the eclipse of the secondary diminishes the magnitude by 0.27.[5]

The primary, component A, is a magnitude 5.85B-type star with astellar classification of B8 III-IVe,[4] suggesting it may be part way along the path ofevolving into agiant star from asubgiant. It has about 3.6 times themass of the Sun and 4.4 times theSun's radius,[9] although it may be tidally deformed since its radius is 86%[10] of theRoche radius.[13] With an estimated age of 158 million years, it has aprojected rotational velocity of 112 km/s.[4]

Component B is a magnitude 7.57[4]B-type main sequence star with a class of B8.5 V.[5] It has 2.6 times the Sun's mass and 2.16 times the radius of the Sun. The star is filling 60% of its Roche radius.[10]

References

[edit]
  1. ^MAST: Barbara A. Mikulski Archive for Space Telescopes, Space Telescope Science Institute, retrieved8 December 2021.
  2. ^abcdeVallenari, A.; et al. (Gaia collaboration) (2023)."Gaia Data Release 3. Summary of the content and survey properties".Astronomy and Astrophysics.674: A1.arXiv:2208.00211.Bibcode:2023A&A...674A...1G.doi:10.1051/0004-6361/202243940.S2CID 244398875. Gaia DR3 record for this source atVizieR.
  3. ^abSamus’, N. N.; Kazarovets, E. V.; Durlevich, O. V.; Kireeva, N. N.; Pastukhova, E. N. (January 2017), "General catalogue of variable stars: Version GCVS 5.1",Astronomy Reports,61 (1):80–88,Bibcode:2017ARep...61...80S,doi:10.1134/S1063772917010085,ISSN 1063-7729,S2CID 255195566.
  4. ^abcdefghTorres, G.; et al. (February 2010), "Accurate masses and radii of normal stars: modern results and applications",The Astronomy and Astrophysics Review,18 (1–2):67–126,arXiv:0908.2624,Bibcode:2010A&ARv..18...67T,doi:10.1007/s00159-009-0025-1,S2CID 14006009.
  5. ^abcMalkov, O. Yu.; et al. (February 2006), "A catalogue of eclipsing variables",Astronomy and Astrophysics,446 (2):785–789,Bibcode:2006A&A...446..785M,doi:10.1051/0004-6361:20053137,hdl:10995/73280.
  6. ^abNicolet, B. (1978), "Photoelectric photometric Catalogue of homogeneous measurements in the UBV System",Astronomy and Astrophysics Supplement Series,34:1–49,Bibcode:1978A&AS...34....1N.
  7. ^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:1208.3048,Bibcode:2012A&A...546A..61D,doi:10.1051/0004-6361/201219219,S2CID 59451347, A61.
  8. ^abPourbaix, D.; Tokovinin, A. A.; Batten, A. H.; Fekel, F. C.; Hartkopf, W. I.; et al. (2004), "SB9: The ninth catalogue of spectroscopic binary orbits",Astronomy & Astrophysics,424 (2):727–732,arXiv:astro-ph/0406573,Bibcode:2004A&A...424..727P,doi:10.1051/0004-6361:20041213,S2CID 119387088.
  9. ^abBrown, Timothy M. (January 2010), "Radii of Rapidly Rotating Stars, with Application to Transiting-Planet Hosts",The Astrophysical Journal,709 (1):535–545,arXiv:0912.1639,Bibcode:2010ApJ...709..535B,doi:10.1088/0004-637X/709/1/535,S2CID 119253009.
  10. ^abcdEker, Z.; et al. (April 2015), "Main-Sequence Effective Temperatures from a Revised Mass-Luminosity Relation Based on Accurate Properties",The Astronomical Journal,149 (4): 16,arXiv:1501.06585,Bibcode:2015AJ....149..131E,doi:10.1088/0004-6256/149/4/131,S2CID 118740259, 131.
  11. ^Jordi, C.; Ribas, I.; Torra, J.; Gimenez, A. (October 1997), "Photometric versus empirical surface gravities of eclipsing binaries.",Astronomy and Astrophysics,326:1044–1054,Bibcode:1997A&A...326.1044J.
  12. ^"chi02 Hya",SIMBAD,Centre de données astronomiques de Strasbourg, retrieved2017-03-17.
  13. ^Pols, Onno R.; et al. (August 1997), "Further critical tests of stellar evolution by means of double-lined eclipsing binaries",Monthly Notices of the Royal Astronomical Society,289 (4):869–881,Bibcode:1997MNRAS.289..869P,doi:10.1093/mnras/289.4.869.
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