# Theta Centauri

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Star in the constellation Centaurus

Theta Centauri Location of θ Centauri (circled) Observation data Epoch J2000.0 Equinox J2000.0 Constellation Centaurus Right ascension 14h 06m 40.94752s[1] Declination −36° 22′ 11.8371″[1] Apparent magnitude (V) +2.06[2] Characteristics Evolutionary stage Red clump[3] Spectral type K0 III[4] U−B color index +0.90[2] B−V color index +0.99[2] Astrometry Radial velocity (Rv) +1.3[5] km/s Proper motion (μ) RA: −520.53[1] mas/yr[1] Dec.: −518.06 mas/yr[1] Parallax (π) 55.45±0.20 mas[1] Distance 58.8 ± 0.2 ly (18.03 ± 0.07 pc) Absolute magnitude (MV) 0.87[6] Details Mass 1.32±0.08[7] M☉ Radius 10.96±0.20[7] R☉ Luminosity 56.0+2.6 −2.5[3][a] L☉ Surface gravity (log g) 2.61±0.09[8] cgs Temperature 4,853±41[8] K Metallicity [Fe/H] −0.047±0.032[8] dex Other designations Menkent, θ Cen, Theta Cen, 5 Centauri, CD−35° 9260, FK5 520, GJ 539, HD 123139, HIP 68933, HR 5288, SAO 205188, LHS 2858[9] Database references SIMBAD data

**Theta Centauri** is a single[10] [star](/source/Star) in the southern [constellation](/source/Constellation) of [Centaurus](/source/Centaurus), the [centaur](/source/Centaur). It has the official name **Menkent**, pronounced [/ˈmɛŋkɛnt/](https://en.wikipedia.org/wiki/Help:IPA/English);[11][12] *Theta Centauri* is its [Bayer designation](/source/Bayer_designation), which is [Latinized](/source/Romanization_of_Greek) from **θ Centauri** and abbreviated Theta Cen or θ Cen. With an [apparent visual magnitude](/source/Apparent_magnitude) of +2.06,[2] it is the [fourth-brightest member of the constellation](/source/List_of_stars_in_Centaurus). Based on [parallax](/source/Stellar_parallax) measurements obtained during the [Hipparcos](/source/Hipparcos) mission, it is about 58.8 [light-years](/source/Light-year) (18.0 [parsecs](/source/Parsec)) distant.[1] It has a relatively high [proper motion](/source/Proper_motion), traversing the [celestial sphere](/source/Celestial_sphere) at the rate of 0.73 arcsecond/yr.[13] This suggests that Menkent may have originated in the outer disk of the [Milky Way](/source/Milky_Way) and is merely passing through the solar neighborhood.[14]

## Nomenclature

*θ Centauri*, [Latinised](/source/Latinisation_of_names) to *Theta Centauri*, is the star's [Bayer designation](/source/Bayer_designation).

It bore the traditional name of *Menkent* derived from the [Arabic](/source/Arabic) word مَنْكِب‎ (mankib) for "shoulder" (of the Centaur), apparently blended with a shortened form of "kentaurus" (centaur). In 2016, the [International Astronomical Union](/source/International_Astronomical_Union) organized a [Working Group on Star Names](/source/IAU_Working_Group_on_Star_Names) (WGSN)[15] to catalog and standardize proper names for stars. The WGSN approved the name *Menkent* for this star on 21 August 2016 and it is now so included in the List of IAU-approved Star Names.[12]

In [Chinese](/source/Chinese_astronomy), 庫樓 (*Kù Lóu*), meaning *[arsenal](/source/Horn_(Chinese_constellation))*, refers to an [asterism](/source/Asterism_(astronomy)) consisting of Theta Centauri, [Zeta Centauri](/source/Zeta_Centauri), [Eta Centauri](/source/Eta_Centauri), [2 Centauri](/source/2_Centauri), [HD 117440](/source/HD_117440), [Xi¹ Centauri](/source/Xi1_Centauri), [Gamma Centauri](/source/Gamma_Centauri), [Tau Centauri](/source/Tau_Centauri), [D Centauri](/source/D_Centauri) and [Sigma Centauri](/source/Sigma_Centauri).[16] Consequently, the [Chinese name](/source/Chinese_star_names) for Theta Centauri itself is 庫樓三 (*Kù Lóu sān*, English: the Third Star of Arsenal).[17]

## Properties

This is an [evolved](/source/Stellar_evolution) [giant star](/source/Giant_star) with a [stellar classification](/source/Stellar_classification) of K0 III[4] and 1.27 times the [mass of the Sun](/source/Mass_of_the_Sun). It is believed to be fusing helium into carbon and heavier elements within its core, qualifying it as a [red clump](/source/Red_clump) star.[3] It is a southern analog to [Pollux](/source/Pollux_(star)), the brightest star in [Gemini](/source/Gemini_(constellation)) and the closest giant to the Sun.[14] Menkent is 11 times larger than the Sun[7] and 56 times more luminous.[3] The [outer envelope](/source/Stellar_atmosphere) has an [effective temperature](/source/Effective_temperature) of 4,853 [K](/source/Kelvin),[8] giving it the orange-hued glow of a cool, [K-type star](/source/K-type_star).[18] Soft X-ray emission has been detected from this star, which has an estimated X-ray luminosity of 1.4 × 1027 erg s−1.[19]

## See also

- [List of nearest giant stars](/source/List_of_nearest_giant_stars)

## Notes

1. **[^](#cite_ref-luminosity_8-0)** Calculated using [absolute bolometric magnitude](/source/Absolute_bolometric_magnitude) of +0.37±0.05 via the equation 100.4(4.74−Mbol).

## 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) [***f***](#cite_ref-aaa474_2_653_1-5) 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) [***c***](#cite_ref-clpl4_99_2-2) [***d***](#cite_ref-clpl4_99_2-3) 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-Fuhrmann2012_3-0) [***b***](#cite_ref-Fuhrmann2012_3-1) [***c***](#cite_ref-Fuhrmann2012_3-2) [***d***](#cite_ref-Fuhrmann2012_3-3) Fuhrmann, K.; Chini, R. (2012). ["Multiplicity among F-type Stars"](https://doi.org/10.1088%2F0067-0049%2F203%2F2%2F30). *The Astrophysical Journal Supplement*. **203** (2): 20. [Bibcode](/source/Bibcode_(identifier)):[2012ApJS..203...30F](https://ui.adsabs.harvard.edu/abs/2012ApJS..203...30F). [doi](/source/Doi_(identifier)):[10.1088/0067-0049/203/2/30](https://doi.org/10.1088%2F0067-0049%2F203%2F2%2F30). 30.

1. ^ [***a***](#cite_ref-aj132_1_161_4-0) [***b***](#cite_ref-aj132_1_161_4-1) Gray, R. O.; et al. (July 2006). "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 parsecs: The Northern Sample I". *The Astronomical Journal*. **132** (1): 161–170. [arXiv](/source/ArXiv_(identifier)):[astro-ph/0603770](https://arxiv.org/abs/astro-ph/0603770). [Bibcode](/source/Bibcode_(identifier)):[2006AJ....132..161G](https://ui.adsabs.harvard.edu/abs/2006AJ....132..161G). [doi](/source/Doi_(identifier)):[10.1086/504637](https://doi.org/10.1086%2F504637). [S2CID](/source/S2CID_(identifier)) [119476992](https://api.semanticscholar.org/CorpusID:119476992).

1. **[^](#cite_ref-scfs_5-0)** Wielen, R.; et al. (1999). "Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions". *Veröff. Astron. Rechen-Inst. Heidelb*. **35** (35). Astronomisches Rechen-Institut Heidelberg: 1. [Bibcode](/source/Bibcode_(identifier)):[1999VeARI..35....1W](https://ui.adsabs.harvard.edu/abs/1999VeARI..35....1W).

1. **[^](#cite_ref-aaa343_222_6-0)** Elgarøy, Øystein; et al. (March 1999). "The Wilson-Bappu effect of the MgII K line - dependence on stellar temperature, activity and metallicity". *Astronomy and Astrophysics*. **343**: 222–228. [Bibcode](/source/Bibcode_(identifier)):[1999A&A...343..222E](https://ui.adsabs.harvard.edu/abs/1999A&A...343..222E).

1. ^ [***a***](#cite_ref-Rudrasingam2026_7-0) [***b***](#cite_ref-Rudrasingam2026_7-1) [***c***](#cite_ref-Rudrasingam2026_7-2) Rudrasingam, Jonatan; Bedding, Timothy R; Pope, Benjamin J S; Pedersen, May Gade; Lund, Mikkel N; White, Timothy R; Hey, Daniel (2026-02-28). ["Halo photometry and asteroseismology for 98 of the brightest stars observed by 'TESS'"](https://doi.org/10.1093%2Fmnras%2Fstag413). *[Monthly Notices of the Royal Astronomical Society](/source/Monthly_Notices_of_the_Royal_Astronomical_Society)*. **547** (4) stag413. [Oxford University Press](/source/Oxford_University_Press) (OUP). [arXiv](/source/ArXiv_(identifier)):[2602.22472](https://arxiv.org/abs/2602.22472). [Bibcode](/source/Bibcode_(identifier)):[2026MNRAS.547ag413R](https://ui.adsabs.harvard.edu/abs/2026MNRAS.547ag413R). [doi](/source/Doi_(identifier)):[10.1093/mnras/stag413](https://doi.org/10.1093%2Fmnras%2Fstag413). [ISSN](/source/ISSN_(identifier)) [0035-8711](https://search.worldcat.org/issn/0035-8711).

1. ^ [***a***](#cite_ref-ottoni_9-0) [***b***](#cite_ref-ottoni_9-1) [***c***](#cite_ref-ottoni_9-2) [***d***](#cite_ref-ottoni_9-3) Ottoni, G.; et al. (2022-01-01). "CORALIE radial-velocity search for companions around evolved stars (CASCADES). I. Sample definition and first results: Three new planets orbiting giant stars". *Astronomy and Astrophysics*. **657**: A87. [arXiv](/source/ArXiv_(identifier)):[2201.01528](https://arxiv.org/abs/2201.01528). [Bibcode](/source/Bibcode_(identifier)):[2022A&A...657A..87O](https://ui.adsabs.harvard.edu/abs/2022A&A...657A..87O). [doi](/source/Doi_(identifier)):[10.1051/0004-6361/202040078](https://doi.org/10.1051%2F0004-6361%2F202040078). [ISSN](/source/ISSN_(identifier)) [0004-6361](https://search.worldcat.org/issn/0004-6361). [Theta Centauri's database entry](https://vizier.cds.unistra.fr/viz-bin/VizieR?-source=J/A+A/657/A87&HD=123139) at [VizieR](/source/VizieR).

1. **[^](#cite_ref-SIMBAD_10-0)** ["tet Cen"](http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=tet+Cen). *[SIMBAD](/source/SIMBAD)*. [Centre de données astronomiques de Strasbourg](/source/Centre_de_donn%C3%A9es_astronomiques_de_Strasbourg). Retrieved 2012-03-01.

1. **[^](#cite_ref-Furhmann_11-0)** Fuhrmann, K.; et al. (February 2017). ["Multiplicity among Solar-type Stars"](https://doi.org/10.3847%2F1538-4357%2F836%2F1%2F139). *The Astrophysical Journal*. **836** (1): 139. [Bibcode](/source/Bibcode_(identifier)):[2017ApJ...836..139F](https://ui.adsabs.harvard.edu/abs/2017ApJ...836..139F). [doi](/source/Doi_(identifier)):[10.3847/1538-4357/836/1/139](https://doi.org/10.3847%2F1538-4357%2F836%2F1%2F139). [ISSN](/source/ISSN_(identifier)) [0004-637X](https://search.worldcat.org/issn/0004-637X).

1. **[^](#cite_ref-Kunitzsch_12-0)** Kunitzsch, Paul; Smart, Tim (2006). *A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations* (2nd rev. ed.). Cambridge, Massachusetts: Sky Pub. [ISBN](/source/ISBN_(identifier)) [978-1-931559-44-7](https://en.wikipedia.org/wiki/Special:BookSources/978-1-931559-44-7).

1. ^ [***a***](#cite_ref-IAU-LSN_13-0) [***b***](#cite_ref-IAU-LSN_13-1) ["Naming Stars"](https://web.archive.org/web/20250310063743/https://www.iau.org/public/themes/naming_stars/). IAU.org. Archived from [the original](https://www.iau.org/public/themes/naming_stars/) on 10 March 2025. Retrieved 18 June 2018.

1. **[^](#cite_ref-Bakos_et_al_2002_14-0)** Bakos, Gáspár Á.; et al. (July 2002). "Revised Coordinates and Proper Motions of the Stars in the Luyten Half-Second Catalog". *The Astrophysical Journal Supplement Series*. **141** (1): 187–193. [arXiv](/source/ArXiv_(identifier)):[astro-ph/0202164](https://arxiv.org/abs/astro-ph/0202164). [Bibcode](/source/Bibcode_(identifier)):[2002ApJS..141..187B](https://ui.adsabs.harvard.edu/abs/2002ApJS..141..187B). [doi](/source/Doi_(identifier)):[10.1086/340115](https://doi.org/10.1086%2F340115). [S2CID](/source/S2CID_(identifier)) [36667868](https://api.semanticscholar.org/CorpusID:36667868).

1. ^ [***a***](#cite_ref-kaler_15-0) [***b***](#cite_ref-kaler_15-1) Kaler, James B. ["MENKENT (Theta Centauri)"](http://stars.astro.illinois.edu/sow/menkent.html). *Stars*. University of Illinois. Retrieved 2012-03-01.

1. **[^](#cite_ref-WGSN_16-0)** ["IAU Working Group on Star Names (WGSN)"](https://web.archive.org/web/20160610172014/https://www.iau.org/science/scientific_bodies/working_groups/280/). Archived from [the original](https://www.iau.org/science/scientific_bodies/working_groups/280/) on 10 June 2016. Retrieved 22 May 2016.

1. **[^](#cite_ref-17)** (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-18)** (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) 2011-01-30 at the [Wayback Machine](/source/Wayback_Machine), Hong Kong Space Museum. Accessed on line November 23, 2010.

1. **[^](#cite_ref-csiro_19-0)** ["The Colour of Stars"](https://web.archive.org/web/20131203222826/http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html). *Australia Telescope, Outreach and Education*. Commonwealth Scientific and Industrial Research Organisation. December 21, 2004. Archived from [the original](http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html) on 2013-12-03. Retrieved 2012-01-16.

1. **[^](#cite_ref-aaa335_591_20-0)** Schroeder, K.-P.; et al. (July 1998). "X-ray activity and evolutionary status of late-type giants". *Astronomy and Astrophysics*. **335**: 591–595. [Bibcode](/source/Bibcode_(identifier)):[1998A&A...335..591S](https://ui.adsabs.harvard.edu/abs/1998A&A...335..591S).

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 [Theta Centauri](https://en.wikipedia.org/wiki/Theta_Centauri) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Theta_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.