# HD 120987

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Binary star system in the constellation Centaurus

This article is about y Centauri; not to be confused with [γ (gamma) Centauri](/source/Gamma_Centauri) or [Y Centauri](/source/HIP_70969).

HD 120987 Observation data Epoch J2000 Equinox J2000 Constellation Centaurus[1] Right ascension 13h 53m 32.76039s[2] Declination −35° 39′ 51.3200″[2] Apparent magnitude (V) 5.565[3] (6.27 / 6.38)‍[4] Characteristics Spectral type F4V (F0V + F1V)[5] U−B color index −0.03[6] B−V color index +0.44[6] Astrometry Radial velocity (Rv) −8.00±7.40[7] km/s Proper motion (μ) RA: −83.39[2] mas/yr Dec.: −25.36[2] mas/yr Parallax (π) 19.13±0.93 mas[2] Distance 170 ± 8 ly (52 ± 3 pc) Absolute magnitude (MV) +1.84[1] Orbit[4] 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 Mass 1.56[8] M☉ HD 120987 B Mass 1.53[8] M☉ Other designations CD−35°9090, HD 120987, HIP 67819, HR 5222, SAO 204955[3] Database references SIMBAD data

**HD 120987** (*y Centauri* or *y Cen*) is a [star system](/source/Star_system) located in the [constellation](/source/Constellation) [Centaurus](/source/Centaurus). HD 120987 is a quintuple [star system](/source/Star_system) located 50 pc (163 [light years](/source/Light_years)) from the [Sun](/source/Sun). The system has an apparent magnitude of 5.565.[3] Based on the system's [parallax](/source/Stellar_parallax), it is located some 172 light-years (52 parsecs) away.[2]

HD 120987 appears to be a single [F-type star](/source/F-type_star) with the [spectral classification](/source/Spectral_classification) F4V, but closer inspection reveals it to be two similar [F-type main-sequence stars](/source/F-type_main-sequence_star) with spectral classifications of F0V and F1V, respectively.[5] The two orbit each other every 373 years, and are separated by 1.519 arcseconds while taking a very [eccentric](/source/Orbital_eccentricity) orbit.[4]

## References

1. ^ [***a***](#cite_ref-xhip_1-0) [***b***](#cite_ref-xhip_1-1) Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". *Astronomy Letters*. **38** (5): 331. [arXiv](/source/ArXiv_(identifier)):[1108.4971](https://arxiv.org/abs/1108.4971). [Bibcode](/source/Bibcode_(identifier)):[2012AstL...38..331A](https://ui.adsabs.harvard.edu/abs/2012AstL...38..331A). [doi](/source/Doi_(identifier)):[10.1134/S1063773712050015](https://doi.org/10.1134%2FS1063773712050015).

1. ^ [***a***](#cite_ref-HIP_2-0) [***b***](#cite_ref-HIP_2-1) [***c***](#cite_ref-HIP_2-2) [***d***](#cite_ref-HIP_2-3) [***e***](#cite_ref-HIP_2-4) [***f***](#cite_ref-HIP_2-5) van Leeuwen, F.; et al. (2007). ["Validation of the new Hipparcos reduction"](http://www.aanda.org/index.php?option=com_article&access=bibcode&Itemid=129&bibcode=2007A%2526A...474..653VFUL). *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-SIMBAD_3-0) [***b***](#cite_ref-SIMBAD_3-1) [***c***](#cite_ref-SIMBAD_3-2) ["* y Cen"](http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=%2A+y+Cen). *[SIMBAD](/source/SIMBAD)*. [Centre de données astronomiques de Strasbourg](/source/Centre_de_donn%C3%A9es_astronomiques_de_Strasbourg). Retrieved 19 July 2017.

1. ^ [***a***](#cite_ref-ORB6_4-0) [***b***](#cite_ref-ORB6_4-1) [***c***](#cite_ref-ORB6_4-2) ["Sixth Catalog of Orbits of Visual Binary Stars"](https://web.archive.org/web/20170801102553/http://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/wds/orb6). United States Naval Observatory. Archived from [the original](http://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/wds/orb6) on 1 August 2017. Retrieved 19 July 2017.

1. ^ [***a***](#cite_ref-Cvetkovic_5-0) [***b***](#cite_ref-Cvetkovic_5-1) Cvetkovic, Z.; Ninkovic, S. (2010). ["On the Component Masses of Visual Binaries"](https://doi.org/10.2298%2FSAJ1080071C). *Serbian Astronomical Journal*. **180** (180): 71. [Bibcode](/source/Bibcode_(identifier)):[2010SerAJ.180...71C](https://ui.adsabs.harvard.edu/abs/2010SerAJ.180...71C). [doi](/source/Doi_(identifier)):[10.2298/SAJ1080071C](https://doi.org/10.2298%2FSAJ1080071C).

1. ^ [***a***](#cite_ref-Cousins_6-0) [***b***](#cite_ref-Cousins_6-1) 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](/source/Bibcode_(identifier)):[1970MNSSA..29....7C](https://ui.adsabs.harvard.edu/abs/1970MNSSA..29....7C).

1. **[^](#cite_ref-Kharchenko_7-0)** 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](/source/ArXiv_(identifier)):[0705.0878](https://arxiv.org/abs/0705.0878). [Bibcode](/source/Bibcode_(identifier)):[2007AN....328..889K](https://ui.adsabs.harvard.edu/abs/2007AN....328..889K). [doi](/source/Doi_(identifier)):[10.1002/asna.200710776](https://doi.org/10.1002%2Fasna.200710776). [S2CID](/source/S2CID_(identifier)) [119323941](https://api.semanticscholar.org/CorpusID:119323941).

1. ^ [***a***](#cite_ref-Tokovinin_8-0) [***b***](#cite_ref-Tokovinin_8-1) Tokovinin, Andrei (2014). "From Binaries to Multiples. II. Hierarchical Multiplicity of F and G Dwarfs". *The Astronomical Journal*. **147** (4): 87. [arXiv](/source/ArXiv_(identifier)):[1401.6827](https://arxiv.org/abs/1401.6827). [Bibcode](/source/Bibcode_(identifier)):[2014AJ....147...87T](https://ui.adsabs.harvard.edu/abs/2014AJ....147...87T). [doi](/source/Doi_(identifier)):[10.1088/0004-6256/147/4/87](https://doi.org/10.1088%2F0004-6256%2F147%2F4%2F87). [S2CID](/source/S2CID_(identifier)) [56066740](https://api.semanticscholar.org/CorpusID:56066740).

v t e Constellation of Centaurus List of stars in Centaurus Centaurus in Chinese astronomy Stars Bayer α A (Rigil Kentaurus) B (Toliman) C (Proxima Centauri) β (Hadar) γ δ ε ζ (Leepwal) η θ (Menkent) ι (Kulou) κ λ μ ν (Heng) ξ1 ξ2 ο1 ο2 π ρ σ τ υ1 υ2 φ χ ψ x1 x2 C3 D E F G H J K M N Q Flamsteed 1 (i) 2 (g) 3 (k) 4 (h) Variable R T V Y RR SV SX BV DY UY V346 V553 V744 V752 V761 (a) V763 (C1) V766 V779 (Krzemiński's star) V803 V810 V816 (Przybylski's Star) V831 V842 V885 V886 V863 V1032 V1369 V1400 V1935 HR 4460 (A) 4466 (C2) 4499 4522 4523 4537 (j) 4546 (B) 4721 4748 (u) 4796 4817 (l) 4831 (w) 4874 (p) 4888 (e) 4889 (n) 4940 (f) 4979 4989 5006 (r) 5041 (m) 5089 (d) 5174 (z) 5222 (y) 5224 5241 5297 5358 (v) 5371 5471 (b) 5485 (c1) 5489 (c2) HD 97413 98176 100453 101581 101930 102117 (Uklun) 103197 107914 108236 109749 110113 113538 113766 114386 114729 115600 116434 (Matza) 117207 117618 (Dofida) 117939 120411 121228 121504 124448 (Popper's Star) 125072 125595 131399 Other 2MASS J1126−5003 2M1207 Gaia BH2 HD 131399 Ab PSR B1259−63 PSR J1311−3430 TOI-763 WASP-15 (Nyamien) WASP-41 WASP-42 WASP-167/KELT-13 Exoplanets 2M1207b b Centauri b HD 101930 b HD 102117 b (Leklsullun) HD 103197 b HD 109749 b HD 113538 b c HD 114386 b HD 114729 b HD 117207 b HD 117618 b (Noifasui) HD 121504 b HIP 65426 b (Najsakopajk) HIP 67522 b NGTS-13b Proxima Centauri b c d WASP-15b (Asye) Star clusters NGC 3766 4230 4507 5281 5286 5316 5460 5617 5662 Other IC 2944 ω Centauri Scorpius–Centaurus association Stock 16 Nebulae NGC 3918 5307 Other Boomerang Nebula Fleming 1 G292.0+1.8 G306.3-0.9 Gum 41 IC 2944 IRAS 13208−6020 RCW 79 RCW 86 Southern Crab Nebula SuWt 2 Galaxies NGC 3557 3568 3749 3783 4444 4603 4622 4650A 4683 4696 4706 4709 4729 4730 4743 4744 4909 4930 4945 4976 5011 A 5026 5064 5082 5090 5091 5102 5114 5121 5128 (Centaurus A) 5161 5206 5253 5266 5291 5398 5408 5419 5483 5516 Other ESO 269-57 ESO 325-4 ESO 383-76 ESO 444-46 Fourcade-Figueroa Object IC 3370 IC 4214 IC 4329A IRAS 13224−3809 J1144−4308 LEDA 677373 PKS 1144−379 PKS 1353−341 PKS 1424−418 Galaxy clusters Abell S740 Centaurus Cluster Shapley Supercluster Astronomical events GW190521 SN 185 SN 1895B (Z) SN 1972E SN 1986G J1407b SN 2019so Category

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