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HD 120987 (y Centauri or y Cen) is a star system located in the constellation Centaurus. HD 120987 is a quintuple star system located 50 pc (163 light years) from the Sun. The system has an apparent magnitude of 5.565.[2] Based on the system's parallax, it is located some 172 light-years (52 parsecs) away.[1]

This article is about y Centauri. Not to be confused with γ (gamma) Centauri. For the variable star, see Y Centauri.
HD 120987
Observation data
Epoch J2000      Equinox J2000
Constellation Centaurus
Right ascension 13h 53m 32.76039s[1]
Declination −35° 39′ 51.3200″[1]
Apparent magnitude (V) 5.565[2]
(6.27 / 6.38)[3]
Characteristics
Spectral type F4V (F0V + F1V)[4]
U−B color index -0.03[5]
B−V color index +0.44[5]
Astrometry
Radial velocity (Rv)-8.00 ± 7.40[6] km/s
Proper motion (μ) RA: -83.39[1] mas/yr
Dec.: -25.36[1] mas/yr
Parallax (π)19.13 ± 0.93 mas[1]
Distance170 ± 8 ly
(52 ± 3 pc)
Orbit[3]
Period (P)373.0 yr
Semi-major axis (a)1.519″
Eccentricity (e)0.775
Inclination (i)74.2°
Longitude of the node (Ω)112.3°
Periastron epoch (T)B 1958.57
Argument of periastron (ω)
(secondary)		90.7°
Details
HD 120987 A
Mass1.56[7] M☉
HD 120987 B
Mass1.53[7] M☉
Other designations
CD−35° 9090, HD 120987, HIP 67819, HR 5222, SAO 204955[2]
Database references
SIMBADdata

HD 120987 appears to be a single F-type star with the spectral classification F4V, but closer inspection reveals it to be two similar F-type main-sequence stars with spectral classifications of F0V and F1V, respectively.[4] The two orbit each other every 373 years, and are separated by 1.519 arcseconds while taking a very eccentric orbit.[3]


References


  1. van Leeuwen, F.; et al. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.
  2. "* y Cen". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 19 July 2017.
  3. "Sixth Catalog of Orbits of Visual Binary Stars". United States Naval Observatory. Retrieved 19 July 2017.
  4. Cvetkovic, Z.; Ninkovic, S. (2010). "On the Component Masses of Visual Binaries". Serbian Astronomical Journal. 180 (180): 71. Bibcode:2010SerAJ.180...71C. doi:10.2298/SAJ1080071C.
  5. Cousins, A. W. J.; Lagerweij, H. C. (1970). "Comparison Stars for Long Period Variables and RY Sagittarii". Monthly Notes of the Astron. Soc. Southern Africa. 29 (7). Bibcode:1970MNSSA..29....7C.
  6. Kharchenko, N. V.; et al. (2007). "Astrophysical supplements to the ASCC-2.5: Ia. Radial velocities of ~55000 stars and mean radial velocities of 516 Galactic open clusters and associations". Astronomische Nachrichten. 328 (9): 889. arXiv:0705.0878. Bibcode:2007AN....328..889K. doi:10.1002/asna.200710776. S2CID 119323941.
  7. Tokovinin, Andrei (2014). "From Binaries to Multiples. II. Hierarchical Multiplicity of F and G Dwarfs". The Astronomical Journal. 147 (4): 87. arXiv:1401.6827. Bibcode:2014AJ....147...87T. doi:10.1088/0004-6256/147/4/87. S2CID 56066740.


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