# Rho Centauri

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Binary star system in the constellation Centaurus

Rho Centauri Location of ρ Centauri (circled) Observation data Epoch J2000.0 Equinox J2000.0 Constellation Centaurus[1] Right ascension 12h 11m 39.12805s[2] Declination −52° 22′ 06.4067″[2] Apparent magnitude (V) +3.97[1] Characteristics Evolutionary stage main sequence Spectral type B3 V[3] U−B color index −0.650[4] B−V color index −0.156±0.008[1] Astrometry Radial velocity (Rv) +15.0±4.1[5] km/s Proper motion (μ) RA: −43.741 mas/yr[2] Dec.: −11.771 mas/yr[2] Parallax (π) 11.8348±0.3746 mas[2] Distance 276 ± 9 ly (84 ± 3 pc) Absolute magnitude (MV) −1.33[1] Orbit[6] Primary A Name B Period (P) 3.626 yr Semi-major axis (a) 0.0440″ Eccentricity (e) 0.619 Inclination (i) 164° Longitude of the node (Ω) 225° Periastron epoch (T) 2019.237 Argument of periastron (ω) (secondary) 54° Details A Mass 5.413[7] M☉ Radius 3.8[8] R☉ Luminosity 810.42[1] L☉ Surface gravity (log g) 3.95[9] cgs Temperature 19,500[9] K Rotational velocity (v sin i) 147[10] km/s Age 23.7±1.4[11] Myr B Mass 3.583[7] M☉ Other designations Rho Cen, ρ Cen, CD−51°6455, HD 105937, HIP 59449, HR 4638, SAO 239737[12] Database references SIMBAD data

**Rho Centauri** is a [binary star](/source/Binary_star)[13] system 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 ρ Centauri, and abbreviated Rho Cen or ρ Cen. This star is visible to the [naked eye](/source/Naked_eye) as a blue-white hued point of light with a combined [apparent visual magnitude](/source/Apparent_visual_magnitude) of +3.97.[1] The system is located approximately 276 [light years](/source/Light_year) from the Sun based on [parallax](/source/Stellar_parallax), and is drifting further away with a [radial velocity](/source/Radial_velocity) of around +15 km/s.[5] It is a [proper motion](/source/Proper_motion) member of the Lower Centaurus–Crux sub-group in the [Scorpius–Centaurus](/source/Scorpius%E2%80%93Centaurus_association) [OB association](/source/Stellar_association), the nearest such association of co-moving massive stars to the Sun.[3]

The primary component of this system is a [B-type main-sequence star](/source/B-type_main-sequence_star) with a [stellar classification](/source/Stellar_classification) of B3 V.[3] It is about 24[11] million years old with a high rate of spin, showing a [projected rotational velocity](/source/Projected_rotational_velocity) of 147 km/s.[10] It has 5.4[7] times the [mass of the Sun](/source/Mass_of_the_Sun) and 3.8[8] times the [Sun's radius](/source/Sun's_radius). The star is radiating 810[1] times the [luminosity of the Sun](/source/Luminosity_of_the_Sun) from its [photosphere](/source/Photosphere) at an [effective temperature](/source/Effective_temperature) of 19,500 K.[9]

The secondary companion is 1.1 magnitudes fainter than the primary, with a [projected separation](/source/Projected_separation) of 5.68 [AU](/source/Astronomical_unit) along a [position angle](/source/Position_angle) of 19.72°, as of 2013.[13] It revolves around the primary star in 3.6 years, on an [ecccentric](/source/Orbital_eccentricity) orbit.[6] The mass is estimated at 3.6 times that of the Sun, or 66% that of the primary.[7]

## References

1. ^ [***a***](#cite_ref-Anderson2012_1-0) [***b***](#cite_ref-Anderson2012_1-1) [***c***](#cite_ref-Anderson2012_1-2) [***d***](#cite_ref-Anderson2012_1-3) [***e***](#cite_ref-Anderson2012_1-4) [***f***](#cite_ref-Anderson2012_1-5) [***g***](#cite_ref-Anderson2012_1-6) 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=59449&-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).

1. ^ [***a***](#cite_ref-GaiaDR3_2-0) [***b***](#cite_ref-GaiaDR3_2-1) [***c***](#cite_ref-GaiaDR3_2-2) [***d***](#cite_ref-GaiaDR3_2-3) Vallenari, A.; et al. (Gaia collaboration) (2023), ["*Gaia* Data Release 3. Summary of the content and survey properties"](https://doi.org/10.1051%2F0004-6361%2F202243940), *Astronomy and Astrophysics*, **674**: A1, [arXiv](/source/ArXiv_(identifier)):[2208.00211](https://arxiv.org/abs/2208.00211), [Bibcode](/source/Bibcode_(identifier)):[2023A&A...674A...1G](https://ui.adsabs.harvard.edu/abs/2023A&A...674A...1G), [doi](/source/Doi_(identifier)):[10.1051/0004-6361/202243940](https://doi.org/10.1051%2F0004-6361%2F202243940), [S2CID](/source/S2CID_(identifier)) [244398875](https://api.semanticscholar.org/CorpusID:244398875). [Gaia DR3 record for this source](https://vizier.cds.unistra.fr/viz-bin/VizieR-4?-source=+I%2F355&-from=nav&-nav=cat%3AI%2F355%26tab%3A%7BI%2F355%2Fgaiadr3%7D%26key%3Asource%3D1355%2Fgaiadr3%26HTTPPRM%3A%26-out.add%3D.%26Source%3D%3D%3D6125166320994675456%26-go+%25%23Sesame%23%25%26) at [VizieR](/source/VizieR).

1. ^ [***a***](#cite_ref-aaa216_1_44_3-0) [***b***](#cite_ref-aaa216_1_44_3-1) [***c***](#cite_ref-aaa216_1_44_3-2) de Geus, E. J.; et al. (June 1989), "Physical parameters of stars in the Scorpio-Centaurus OB association", *Astronomy and Astrophysics*, **216** (1–2): 44–61, [Bibcode](/source/Bibcode_(identifier)):[1989A&A...216...44D](https://ui.adsabs.harvard.edu/abs/1989A&A...216...44D)

1. **[^](#cite_ref-apjs15_4-0)** 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-Gontcharov2006_5-0) [***b***](#cite_ref-Gontcharov2006_5-1) Gontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system", *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-Mason2023_6-0) [***b***](#cite_ref-Mason2023_6-1) Mason, Brian D.; et al. (October 2023), "Speckle Interferometry at SOAR in 2022", *The Astronomical Journal*, **166** (4): 139, [Bibcode](/source/Bibcode_(identifier)):[2023AJ....166..139M](https://ui.adsabs.harvard.edu/abs/2023AJ....166..139M), [doi](/source/Doi_(identifier)):[10.3847/1538-3881/acedaf](https://doi.org/10.3847%2F1538-3881%2Facedaf).

1. ^ [***a***](#cite_ref-Gratton2023_7-0) [***b***](#cite_ref-Gratton2023_7-1) [***c***](#cite_ref-Gratton2023_7-2) [***d***](#cite_ref-Gratton2023_7-3) Gratton, R.; et al. (October 2023), "Multiples among B stars in the Scorpius-Centaurus association", *Astronomy & Astrophysics*, **678**: A93, [arXiv](/source/ArXiv_(identifier)):[2308.09962](https://arxiv.org/abs/2308.09962), [Bibcode](/source/Bibcode_(identifier)):[2023A&A...678A..93G](https://ui.adsabs.harvard.edu/abs/2023A&A...678A..93G), [doi](/source/Doi_(identifier)):[10.1051/0004-6361/202346806](https://doi.org/10.1051%2F0004-6361%2F202346806). [Vizier catalog entry](https://vizier.cds.unistra.fr/viz-bin/VizieR-6?-out.form=%2bH&-source=J/A%2bA/678/A93&HIP=59449)

1. ^ [***a***](#cite_ref-aaa367_521_8-0) [***b***](#cite_ref-aaa367_521_8-1) Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics", *Astronomy and Astrophysics*, **367** (2): 521–524, [arXiv](/source/ArXiv_(identifier)):[astro-ph/0012289](https://arxiv.org/abs/astro-ph/0012289), [Bibcode](/source/Bibcode_(identifier)):[2001A&A...367..521P](https://ui.adsabs.harvard.edu/abs/2001A&A...367..521P), [doi](/source/Doi_(identifier)):[10.1051/0004-6361:20000451](https://doi.org/10.1051%2F0004-6361%3A20000451), [S2CID](/source/S2CID_(identifier)) [425754](https://api.semanticscholar.org/CorpusID:425754).

1. ^ [***a***](#cite_ref-levenhagen2006_9-0) [***b***](#cite_ref-levenhagen2006_9-1) [***c***](#cite_ref-levenhagen2006_9-2) Levenhagen, R. S.; Leister, N. V. (2006), "Spectroscopic analysis of southern B and Be stars", *Monthly Notices of the Royal Astronomical Society*, **371** (1): 252–262, [arXiv](/source/ArXiv_(identifier)):[astro-ph/0606149](https://arxiv.org/abs/astro-ph/0606149), [Bibcode](/source/Bibcode_(identifier)):[2006MNRAS.371..252L](https://ui.adsabs.harvard.edu/abs/2006MNRAS.371..252L), [doi](/source/Doi_(identifier)):[10.1111/j.1365-2966.2006.10655.x](https://doi.org/10.1111%2Fj.1365-2966.2006.10655.x), [S2CID](/source/S2CID_(identifier)) [16492030](https://api.semanticscholar.org/CorpusID:16492030).

1. ^ [***a***](#cite_ref-uesugi_fukuda70_10-0) [***b***](#cite_ref-uesugi_fukuda70_10-1) Uesugi, Akira; Fukuda, Ichiro (1970), "Catalogue of rotational velocities of the stars", *Contributions from the Institute of Astrophysics and Kwasan Observatory*, University of Kyoto, [Bibcode](/source/Bibcode_(identifier)):[1970crvs.book.....U](https://ui.adsabs.harvard.edu/abs/1970crvs.book.....U).

1. ^ [***a***](#cite_ref-mnras410_1_190_11-0) [***b***](#cite_ref-mnras410_1_190_11-1) 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. **[^](#cite_ref-SIMBAD_12-0)** ["rho Cen"](http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=rho+Cen), *[SIMBAD](/source/SIMBAD)*, [Centre de données astronomiques de Strasbourg](/source/Centre_de_donn%C3%A9es_astronomiques_de_Strasbourg), retrieved 2019-10-10.

1. ^ [***a***](#cite_ref-Rizzuto2013_13-0) [***b***](#cite_ref-Rizzuto2013_13-1) Rizzuto, A. C.; et al. (December 2013), "Long-baseline interferometric multiplicity survey of the Sco-Cen OB association", *Monthly Notices of the Royal Astronomical Society*, **436** (2): 1694–1707, [arXiv](/source/ArXiv_(identifier)):[1309.3811](https://arxiv.org/abs/1309.3811), [Bibcode](/source/Bibcode_(identifier)):[2013MNRAS.436.1694R](https://ui.adsabs.harvard.edu/abs/2013MNRAS.436.1694R), [doi](/source/Doi_(identifier)):[10.1093/mnras/stt1690](https://doi.org/10.1093%2Fmnras%2Fstt1690).

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 [Rho Centauri](https://en.wikipedia.org/wiki/Rho_Centauri) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Rho_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.