# Mu Centauri

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Variable star in the constellation Centaurus

Mu Centauri Location of μ Centauri (circled) Observation data Epoch J2000.0 Equinox J2000.0 Constellation Centaurus[1] Right ascension 13h 49m 36.98863s[2] Declination −42° 28′ 25.4296″[2] Apparent magnitude (V) +3.42[3] (+2.92 to +3.49)[4] Characteristics Spectral type B2V:e[5] U−B color index −0.854[3] B−V color index −0.205[3] Variable type γ Cas[4] Astrometry Radial velocity (Rv) +9.2±2.7[6] km/s Proper motion (μ) RA: −24.25[2] mas/yr[2] Dec.: −18.64 mas/yr[2] Parallax (π) 6.45±0.16 mas[2] Distance 510 ± 10 ly (155 ± 4 pc) Absolute magnitude (MV) −2.48[1] Details Mass 9.1±0.2[7] M☉ Radius 4.21 (equatorial) 3.4±0.3 (polar)[8] R☉ Luminosity 2,090[8] L☉ Surface gravity (log g) 3.86 (equatorial) 4.33 (polar)[8] cgs Temperature 17,600 (equatorial) 23,200±200 (polar)[8] K Rotation 11.615 hours[8] Rotational velocity (v sin i) 194[9] km/s Age 19.8±1.7[7] Myr Other designations μ Cen, CD−41°8172, FK5 508, HD 120324, HIP 67472, HR 5193, SAO 224471[10] Database references SIMBAD data

**Mu Centauri** is a [star](/source/Star) in the southern [constellation](/source/Constellation) of [Centaurus](/source/Centaurus). Its name is a [Bayer designation](/source/Bayer_designation) that is [Latinized](/source/Romanization_of_Greek) from μ Centauri, and abbreviated Mu Cen or μ Cen. With the stars [ν](/source/Nu_Centauri) and [φ Centauri](/source/Phi_Centauri), it marks what has been traditionally portrayed as "*dextro Latere*" (the right side) of the Centaur.[11] The [apparent visual magnitude](/source/Apparent_visual_magnitude) of this star is 3.42,[3] making it one of the [brighter members](/source/List_of_stars_in_Centaurus) of the constellation. The distance to this star can be estimated directly using [parallax](/source/Stellar_parallax) measurements, which yield a value of roughly 510 [light years](/source/Light_year) (155 [parsecs](/source/Parsec)) from [Earth](/source/Earth).[2] It is drifting further away with a [radial velocity](/source/Radial_velocity) of +9 km/s.[6]

A [visual band](/source/Photometric_system#Photometric_letters) [light curve](/source/Light_curve) for Mu Centauri, plotted from data published by Aguayo *et al.* (2018)[12]

The [spectrum](/source/Stellar_spectrum) of Mu Centauri is considered to be a standard for a B2 [Be star](/source/Be_star) with the [stellar classification](/source/Stellar_classification) of B2V:e.[5] The 'e' suffix is used to mark the presence of [emission lines](/source/Emission_line), caused by a circumstellar disk of hot gas that was formed from material ejected from the star. Mu Centauri is a pulsating variable star that has multiple non-radial cycles with a primary period of 0.503 days. Three other pulsation cycles have a similar period, while two have a shorter interval of about 0.28 days. It undergoes outburst events that result in the transfer of additional material to the surrounding disk.[13] During these outbursts, the star can experience transient periodicities.[14] Mu Centauri is classified as a [Gamma Cassiopeiae type](/source/Gamma_Cassiopeiae_variable) [variable star](/source/Variable_star) and its brightness varies from magnitude +2.92 to +3.49.[4]

This star is spinning rapidly, with a [projected rotational velocity](/source/Projected_rotational_velocity) of 194[9] km s−1 and is completing a full rotation in about 11.615 hours. The equatorial [azimuthal](/source/Azimuth) velocity is around 85% of the critical velocity where the star would start to break up, resulting a pronounced [equatorial bulge](/source/Equatorial_bulge) that is about 26% wider than the radius at the poles. Because of the [oblate spheroidal](/source/Oblate_spheroid) shape of this star, the polar region is at a higher temperature than the equator—23,000 K versus 17,600 K respectively. Likewise, the gravitational force at the poles is greater than along the equator. The axis of rotation of the star is tilted by an angle of about (19 ± 3)° to the line of sight from the Earth.[8]

At an estimated age of nearly 20 million years,[7] this star is around 55–65% of the way through its evolutionary period on the [main sequence](/source/Main_sequence) of core [hydrogen burning](/source/Hydrogen_burning) stars.[15] It has around nine[7] times the mass of the Sun and four[15] times the Sun's radius, but emits over 2,000[8] times as much energy as the Sun. The outer atmosphere has a mean [effective temperature](/source/Effective_temperature) of 22,410 K,[15] giving the star a blue-white hue.[16]

This star is a [proper motion](/source/Proper_motion) member of the Upper Centaurus–Lupus sub-group in the [Scorpius–Centaurus](/source/Scorpius%E2%80%93Centaurus_association) [OB association](/source/Stellar_association), the nearest such co-moving association of massive stars to the Sun.[17]

## References

1. ^ [***a***](#cite_ref-Anderson2012_1-0) [***b***](#cite_ref-Anderson2012_1-1) Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", *[Astronomy Letters](/source/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). [XHIP record for this object](https://vizier.cds.unistra.fr/viz-bin/VizieR-4?-ref=VIZ681510a8389ecb&-out.src=V%2F137D%2FXHIP&-nav=cat%3AV%2F137D%26tab%3A{V%2F137D%2FXHIP}%26key%3Asource%3DV%2F137D%2FXHIP%26HTTPPRM%3A&-source=V%2F137D%2FXHIP&-out=HIP&HIP=67472&-out=Comp&-out=Gr&-out=RAJ2000&-out=DEJ2000&-out=Dist&-out=X&-out=Y&-out=Z&-out=SpType&-out=Simbad&-out=Hpmag&-out=Lum&-out=Cst) at [VizieR](/source/VizieR).

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1. ^ [***a***](#cite_ref-apjs15_459_3-0) [***b***](#cite_ref-apjs15_459_3-1) [***c***](#cite_ref-apjs15_459_3-2) [***d***](#cite_ref-apjs15_459_3-3) Gutierrez-Moreno, Adelina; Moreno, Hugo (June 1968), "A photometric investigation of the Scorpio-Centaurus association", *Astrophysical Journal Supplement*, **15**: 459, [Bibcode](/source/Bibcode_(identifier)):[1968ApJS...15..459G](https://ui.adsabs.harvard.edu/abs/1968ApJS...15..459G), [doi](/source/Doi_(identifier)):[10.1086/190168](https://doi.org/10.1086%2F190168).

1. ^ [***a***](#cite_ref-gcvs_4-0) [***b***](#cite_ref-gcvs_4-1) [***c***](#cite_ref-gcvs_4-2) Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", *Astronomy Reports*, 5.1, **61** (1): 80–88, [Bibcode](/source/Bibcode_(identifier)):[2017ARep...61...80S](https://ui.adsabs.harvard.edu/abs/2017ARep...61...80S), [doi](/source/Doi_(identifier)):[10.1134/S1063772917010085](https://doi.org/10.1134%2FS1063772917010085), [S2CID](/source/S2CID_(identifier)) [125853869](https://api.semanticscholar.org/CorpusID:125853869).

1. ^ [***a***](#cite_ref-mk_5-0) [***b***](#cite_ref-mk_5-1) Morgan, W. W.; et al. (1978), "Revised MK Spectral Atlas for stars earlier than the sun", *Williams Bay: Yerkes Observatory*, [Bibcode](/source/Bibcode_(identifier)):[1978rmsa.book.....M](https://ui.adsabs.harvard.edu/abs/1978rmsa.book.....M).

1. ^ [***a***](#cite_ref-Gontcharov_2006_6-0) [***b***](#cite_ref-Gontcharov_2006_6-1) Gontcharov, G. A. (2006), "Pulkovo compilation of radial velocities for 35495 stars in a common system", *[Astronomy Letters](/source/Astronomy_Letters)*, **32** (11): 759–771, [arXiv](/source/ArXiv_(identifier)):[1606.08053](https://arxiv.org/abs/1606.08053), [Bibcode](/source/Bibcode_(identifier)):[2006AstL...32..759G](https://ui.adsabs.harvard.edu/abs/2006AstL...32..759G), [doi](/source/Doi_(identifier)):[10.1134/S1063773706110065](https://doi.org/10.1134%2FS1063773706110065), [S2CID](/source/S2CID_(identifier)) [119231169](https://api.semanticscholar.org/CorpusID:119231169).

1. ^ [***a***](#cite_ref-mnras410_1_190_7-0) [***b***](#cite_ref-mnras410_1_190_7-1) [***c***](#cite_ref-mnras410_1_190_7-2) [***d***](#cite_ref-mnras410_1_190_7-3) Tetzlaff, N.; et al. (January 2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun", *[Monthly Notices of the Royal Astronomical Society](/source/Monthly_Notices_of_the_Royal_Astronomical_Society)*, **410** (1): 190–200, [arXiv](/source/ArXiv_(identifier)):[1007.4883](https://arxiv.org/abs/1007.4883), [Bibcode](/source/Bibcode_(identifier)):[2011MNRAS.410..190T](https://ui.adsabs.harvard.edu/abs/2011MNRAS.410..190T), [doi](/source/Doi_(identifier)):[10.1111/j.1365-2966.2010.17434.x](https://doi.org/10.1111%2Fj.1365-2966.2010.17434.x), [S2CID](/source/S2CID_(identifier)) [118629873](https://api.semanticscholar.org/CorpusID:118629873).

1. ^ [***a***](#cite_ref-aaa369_1058_8-0) [***b***](#cite_ref-aaa369_1058_8-1) [***c***](#cite_ref-aaa369_1058_8-2) [***d***](#cite_ref-aaa369_1058_8-3) [***e***](#cite_ref-aaa369_1058_8-4) [***f***](#cite_ref-aaa369_1058_8-5) [***g***](#cite_ref-aaa369_1058_8-6) Rivinius, Th.; et al. (April 2001), "Stellar and circumstellar activity of the Be star mu Centauri. III. Multiline nonradial pulsation modeling", *Astronomy and Astrophysics*, **369**: 1058–1077, [Bibcode](/source/Bibcode_(identifier)):[2001A&A...369.1058R](https://ui.adsabs.harvard.edu/abs/2001A&A...369.1058R), [doi](/source/Doi_(identifier)):[10.1051/0004-6361:20010185](https://doi.org/10.1051%2F0004-6361%3A20010185).

1. ^ [***a***](#cite_ref-coapa239_1_9-0) [***b***](#cite_ref-coapa239_1_9-1) Bernacca, P. L.; Perinotto, M. (1970), "A catalogue of stellar rotational velocities", *Contributi Osservatorio Astronomico di Padova in Asiago*, **239** (1), [Bibcode](/source/Bibcode_(identifier)):[1970CoAsi.239....1B](https://ui.adsabs.harvard.edu/abs/1970CoAsi.239....1B).

1. **[^](#cite_ref-SIMBAD_10-0)** ["mu Cen"](http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=mu+Cen), *[SIMBAD](/source/SIMBAD)*, [Centre de données astronomiques de Strasbourg](/source/Centre_de_donn%C3%A9es_astronomiques_de_Strasbourg), retrieved 2025-12-16.

1. **[^](#cite_ref-Ptolemy_11-0)** ["Star Catalogue of Ptolemy"](https://web.archive.org/web/20071115020105/http://astro.isi.edu/reference/almagest.html), *The Astronomy Corner*, archived from [the original](http://astro.isi.edu/reference/almagest.html) on 2007-11-15, retrieved 2007-11-15.

1. **[^](#cite_ref-Aguayo_12-0)** Aguayo, G.; et al. (October 2018), "Multi-epoch L-band Spectroscopy of the Be Star μ Centauri Prior to Outburst", *The Astronomical Journal*, **156** (4): 174, [Bibcode](/source/Bibcode_(identifier)):[2018AJ....156..174A](https://ui.adsabs.harvard.edu/abs/2018AJ....156..174A), [doi](/source/Doi_(identifier)):[10.3847/1538-3881/aad5db](https://doi.org/10.3847%2F1538-3881%2Faad5db), [hdl](/source/Hdl_(identifier)):[11336/82431](https://hdl.handle.net/11336%2F82431), [S2CID](/source/S2CID_(identifier)) [125167180](https://api.semanticscholar.org/CorpusID:125167180).

1. **[^](#cite_ref-aaa333_125_13-0)** Rivinius, Th.; et al. (May 1998), "Stellar and circumstellar activity of the Be star MU Centauri. I. Line emission outbursts", *Astronomy and Astrophysics*, **333**: 125–140, [Bibcode](/source/Bibcode_(identifier)):[1998A&A...333..125R](https://ui.adsabs.harvard.edu/abs/1998A&A...333..125R).

1. **[^](#cite_ref-aaa411_229_14-0)** Rivinius, Th.; et al. (November 2003), "Non-radially pulsating Be stars", *Astronomy and Astrophysics*, **411** (2): 229–247, [Bibcode](/source/Bibcode_(identifier)):[2003A&A...411..229R](https://ui.adsabs.harvard.edu/abs/2003A&A...411..229R), [doi](/source/Doi_(identifier)):[10.1051/0004-6361:20031285](https://doi.org/10.1051%2F0004-6361%3A20031285).

1. ^ [***a***](#cite_ref-aaa441_1_235_15-0) [***b***](#cite_ref-aaa441_1_235_15-1) [***c***](#cite_ref-aaa441_1_235_15-2) Zorec, J.; et al. (October 2005), "On the evolutionary status of Be stars. I. Field Be stars near the Sun", *Astronomy and Astrophysics*, **441** (1): 235–248, [arXiv](/source/ArXiv_(identifier)):[astro-ph/0509119](https://arxiv.org/abs/astro-ph/0509119), [Bibcode](/source/Bibcode_(identifier)):[2005A&A...441..235Z](https://ui.adsabs.harvard.edu/abs/2005A&A...441..235Z), [doi](/source/Doi_(identifier)):[10.1051/0004-6361:20053051](https://doi.org/10.1051%2F0004-6361%3A20053051), [S2CID](/source/S2CID_(identifier)) [17592657](https://api.semanticscholar.org/CorpusID:17592657).

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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 [Mu Centauri](https://en.wikipedia.org/wiki/Mu_Centauri) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Mu_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.