# Gamma Centauri

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Star in the constellation Centaurus

This article is about γ Centauri; not to be confused with [Y Centauri](/source/HIP_70969) or [y Centauri](/source/HD_120987).

Gamma Centauri Location of γ Centauri (circled) Observation data Epoch J2000 Equinox J2000 Constellation Centaurus Right ascension 12h 41m 31.04008s[1] Declination −48° 57′ 35.5375″[1] Apparent magnitude (V) +2.17[2] (+2.84/+2.94)[3] Characteristics A Evolutionary stage subgiant[4] Spectral type A1IV[5] U−B color index 0.00[6] B−V color index −0.03[6] B Evolutionary stage subgiant[4] Spectral type A0IV[5] U−B color index −0.02[6] B−V color index +0.01[6] Astrometry Radial velocity (Rv) −5.5[7] km/s Proper motion (μ) RA: −185.72[1] mas/yr Dec.: +5.79[1] mas/yr Parallax (π) 25.06±0.28 mas[1] Distance 130 ± 1 ly (39.9 ± 0.4 pc) Absolute magnitude (MV) −0.81[8] Orbit[9] Period (P) 83.57±0.21 yr Semi-major axis (a) 0.869±0.011″ Eccentricity (e) 0.793±0.003 Inclination (i) 113.7±0.7° Longitude of the node (Ω) 2.6±0.7° Periastron epoch (T) 1931.25 ± 0.07 Argument of periastron (ω) (secondary) 187.9±1.5° Details[4] Mass 2.8 M☉ Radius 3.8[a] R☉ Luminosity 95 L☉ Temperature 9,300 K B Mass 2.8 M☉ Radius 3.8[a] R☉ Luminosity 95 L☉ Temperature 9,300 K Other designations Muhlifain, γ Cen, CD−48°7597, GC 17262, HD 110304, HIP 61932, HR 4819, SAO 223603, CCDM J12415-4858, WDS 12415-4858 Database references SIMBAD data A B

**Gamma Centauri** is a [binary star](/source/Binary_star) system in the [southern](/source/Southern_celestial_hemisphere) [constellation](/source/Constellation) of [Centaurus](/source/Centaurus), which is probably part of a wider system together with [Tau Centauri](/source/Tau_Centauri). The system is visible to the naked eye as a single point of light with a combined [apparent visual magnitude](/source/Apparent_visual_magnitude) of +2.17;[2] individually they are third-magnitude stars.[3]

## Nomenclature

Its main name is a [Bayer designation](/source/Bayer_designation) that is [Latinized](/source/Romanization_of_Greek) from γ Centauri, and abbreviated Gamma Cen or γ Cen.

It has the proper name **Muhlifain**,[10] not to be confused with Muliphein, which is [γ Canis Majoris](/source/%CE%93_Canis_Majoris); both names derive from the same Arabic root.

## Characteristics

This system is located at a distance of about 130 [light-years](/source/Light-year) (40 [parsecs](/source/Parsec)) from the [Sun](/source/Sun) based on [parallax](/source/Stellar_parallax). In 2000, the pair had an angular separation of 1.217 [arcseconds](/source/Arcseconds) with a [position angle](/source/Position_angle) of 351.9°.[3] Their positions have been observed since 1897, which is long enough to estimate an [orbital period](/source/Orbital_period) of 84.5 years and a [semimajor axis](/source/Semimajor_axis) of 0.93 arcsecond.[11][9] At the distance of this system, this is equivalent to a physical separation of about 93 [AU](/source/Astronomical_unit).[4]

The stars have [spectral types](/source/Spectral_type) of A1IV and A0IV,[5] suggesting they are [A-type](/source/A-type_star) [subgiant](/source/Subgiant) stars in the process of becoming [giants](/source/Giant_star). The stars have similar characteristics, with an estimated 2.8 times the [Sun's mass](/source/Sun's_mass), around 100 times the [Sun's luminosity](/source/Sun's_luminosity) and an estimated [effective temperature](/source/Effective_temperature) of 9,300 K.[4]

The star [Tau Centauri](/source/Tau_Centauri) very likely makes a widely-separated binary system with Gamma Centauri, it is a [co-moving star](/source/Comoving_and_proper_distances) with an estimated separation of 1.72 light-years (0.53 parsecs). There is a 98% chance that they are gravitationally bound.[12]

## Etymology

In [Chinese astronomy](/source/Chinese_astronomy), 庫樓 (*Kù Lóu*), meaning *[Arsenal](/source/Horn_(Chinese_constellation))*, refers to an [asterism](/source/Asterism_(astronomy)) consisting of γ Centauri, [ζ Centauri](/source/%CE%96_Centauri), [η Centauri](/source/%CE%97_Centauri), [θ Centauri](/source/%CE%98_Centauri), [2 Centauri](/source/2_Centauri), [HD 117440](/source/HD_117440), [ξ1 Centauri](/source/Xi1_Centauri), [τ Centauri](/source/%CE%A4_Centauri), [D Centauri](/source/D_Centauri) and [σ Centauri](/source/%CE%A3_Centauri).[13] Consequently, the [Chinese name](/source/Chinese_star_names) for γ Centauri itself is 庫樓七 (*Kù Lóu qī*, English: the Seventh Star of Arsenal).[14]

The people of [Aranda](/source/Arrernte_people) and [Luritja](/source/Luritja) tribe around [Hermannsburg](/source/Hermannsburg%2C_Northern_Territory), [Central Australia](/source/Central_Australia) named a quadrangular arrangement comprising this star, [δ Cen](/source/Delta_Centauri) (Ma Wei), [δ Cru](/source/Imai_(star)) (Imai) and γ Cru ([Gacrux](/source/Gacrux)) as *Iritjinga* ("The Eagle-hawk").[15]

## Notes

1. ^ [***a***](#cite_ref-radius_10-0) [***b***](#cite_ref-radius_10-1) Calculated, using the [Stefan-Boltzmann law](/source/Stefan-Boltzmann_law) and the star's [effective temperature](/source/Effective_temperature) and luminosity, with respect to the [solar](/source/Sun) nominal effective temperature of 5,772 [K](/source/Kelvin): ( 5 , 772 9 , 300 ) 4 ⋅ 95 = 3.8 R ⊙ . {\displaystyle {\sqrt {{\biggl (}{\frac {5,772}{9,300}}{\biggr )}^{4}\cdot 95}}=3.8\ R_{\odot }.}

## References

1. ^ [***a***](#cite_ref-aaa474_2_653_1-0) [***b***](#cite_ref-aaa474_2_653_1-1) [***c***](#cite_ref-aaa474_2_653_1-2) [***d***](#cite_ref-aaa474_2_653_1-3) [***e***](#cite_ref-aaa474_2_653_1-4) van Leeuwen, F. (November 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-clpl4_99_2-0) [***b***](#cite_ref-clpl4_99_2-1) 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-aaa356_141_3-0) [***b***](#cite_ref-aaa356_141_3-1) [***c***](#cite_ref-aaa356_141_3-2) Fabricius, C.; Makarov, V. V. (April 2000). "Two-colour photometry for 9473 components of close Hipparcos double and multiple stars". *Astronomy and Astrophysics*. **356**: 141–145. [Bibcode](/source/Bibcode_(identifier)):[2000A&A...356..141F](https://ui.adsabs.harvard.edu/abs/2000A&A...356..141F).

1. ^ [***a***](#cite_ref-kaler_4-0) [***b***](#cite_ref-kaler_4-1) [***c***](#cite_ref-kaler_4-2) [***d***](#cite_ref-kaler_4-3) [***e***](#cite_ref-kaler_4-4) Kaler, James B. ["MUHLIFAIN (Gamma Centauri)"](http://stars.astro.illinois.edu/sow/muhlifain.html). *Stars*. [University of Illinois](/source/University_of_Illinois). Retrieved 2011-12-31.

1. ^ [***a***](#cite_ref-Gray_Garrison_1987_5-0) [***b***](#cite_ref-Gray_Garrison_1987_5-1) [***c***](#cite_ref-Gray_Garrison_1987_5-2) Gray, R. O.; Garrison, R. F. (December 1987). ["The Early A-Type Stars: Refined MK Classification, Confrontation with Stroemgren Photometry, and the Effects of Rotation"](https://doi.org/10.1086%2F191237). *Astrophysical Journal Supplement*. **65**: 581. [Bibcode](/source/Bibcode_(identifier)):[1987ApJS...65..581G](https://ui.adsabs.harvard.edu/abs/1987ApJS...65..581G). [doi](/source/Doi_(identifier)):[10.1086/191237](https://doi.org/10.1086%2F191237).

1. ^ [***a***](#cite_ref-marecki1994_6-0) [***b***](#cite_ref-marecki1994_6-1) [***c***](#cite_ref-marecki1994_6-2) [***d***](#cite_ref-marecki1994_6-3) Marecki, A.; Strobel, J.; Strobel, A. (1994). "VizieR Online Data Catalog: Catalogue of stellar abundances (Marecki+ 1986)". *Vizier Online Data Catalog*. [Bibcode](/source/Bibcode_(identifier)):[1994yCat.3121....0M](https://ui.adsabs.harvard.edu/abs/1994yCat.3121....0M).

1. **[^](#cite_ref-rgcrv_7-0)** Evans, D. S. (June 20–24, 1966). Batten, Alan Henry; Heard, John Frederick (eds.). "The Revision of the General Catalogue of Radial Velocities". *Determination of Radial Velocities and Their Applications, Proceedings from IAU Symposium No. 30*. **30**. University of Toronto: [International Astronomical Union](/source/International_Astronomical_Union): 57. [Bibcode](/source/Bibcode_(identifier)):[1967IAUS...30...57E](https://ui.adsabs.harvard.edu/abs/1967IAUS...30...57E).

1. **[^](#cite_ref-schaaf_8-0)** Schaaf, Fred (2008). *The brightest stars: discovering the universe through the sky's most brilliant stars*. [John Wiley and Sons](/source/John_Wiley_and_Sons). p. 262. [Bibcode](/source/Bibcode_(identifier)):[2008bsdu.book.....S](https://ui.adsabs.harvard.edu/abs/2008bsdu.book.....S). [ISBN](/source/ISBN_(identifier)) [978-0-471-70410-2](https://en.wikipedia.org/wiki/Special:BookSources/978-0-471-70410-2).

1. ^ [***a***](#cite_ref-Argyle_et_al_2015_9-0) [***b***](#cite_ref-Argyle_et_al_2015_9-1) Argyle, R. W.; et al. (May 2015). ["Micrometric measures and orbits of southern visual double stars"](https://doi.org/10.1002%2Fasna.201412166). *Astronomische Nachrichten*. **336** (4): 378–387. [Bibcode](/source/Bibcode_(identifier)):[2015AN....336..378A](https://ui.adsabs.harvard.edu/abs/2015AN....336..378A). [doi](/source/Doi_(identifier)):[10.1002/asna.201412166](https://doi.org/10.1002%2Fasna.201412166).

1. **[^](#cite_ref-11)** Paul Kunitzsch (1959). [*Arabische Sternnamen in Europa, von Paul Kunitzsch*](https://books.google.com/books?id=qhtGQwAACAAJ). O. Harrassowitz. p. 188.

1. **[^](#cite_ref-aj122_6_3466_12-0)** Mason, Brian D.; et al. (December 2001). ["The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog"](https://doi.org/10.1086%2F323920). *The Astronomical Journal*. **122** (6): 3466–3471. [Bibcode](/source/Bibcode_(identifier)):[2001AJ....122.3466M](https://ui.adsabs.harvard.edu/abs/2001AJ....122.3466M). [doi](/source/Doi_(identifier)):[10.1086/323920](https://doi.org/10.1086%2F323920).

1. **[^](#cite_ref-apjs192_1_2_13-0)** Shaya, Ed J.; Olling, Rob P. (January 2011). "Very Wide Binaries and Other Comoving Stellar Companions: A Bayesian Analysis of the Hipparcos Catalogue". *The Astrophysical Journal Supplement*. **192** (1): 2. [arXiv](/source/ArXiv_(identifier)):[1007.0425](https://arxiv.org/abs/1007.0425). [Bibcode](/source/Bibcode_(identifier)):[2011ApJS..192....2S](https://ui.adsabs.harvard.edu/abs/2011ApJS..192....2S). [doi](/source/Doi_(identifier)):[10.1088/0067-0049/192/1/2](https://doi.org/10.1088%2F0067-0049%2F192%2F1%2F2). [S2CID](/source/S2CID_(identifier)) [119226823](https://api.semanticscholar.org/CorpusID:119226823).

1. **[^](#cite_ref-14)** (in Chinese) *中國星座神話*, written by 陳久金. Published by 台灣書房出版有限公司, 2005, [ISBN](/source/ISBN_(identifier)) [978-986-7332-25-7](https://en.wikipedia.org/wiki/Special:BookSources/978-986-7332-25-7).

1. **[^](#cite_ref-15)** (in Chinese) [香港太空館 - 研究資源 - 亮星中英對照表](http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_m.htm) [Archived](https://web.archive.org/web/20110130063012/http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_m.htm) January 30, 2011, at the [Wayback Machine](/source/Wayback_Machine), Hong Kong Space Museum. Accessed online November 23, 2010.

1. **[^](#cite_ref-16)** Raymond Haynes; Roslynn D. Haynes; David Malin; Richard McGee (1996), [*Explorers of the Southern Sky: A History of Australian Astronomy*](https://books.google.com/books?id=XoeiJxMmXZ8C), Cambridge: Cambridge University Press, p. 8, [ISBN](/source/ISBN_(identifier)) [978-0-521-36575-8](https://en.wikipedia.org/wiki/Special:BookSources/978-0-521-36575-8)

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