# UY Centauri

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Variable star in the constellation Centaurus

UY Centauri A visual band light curve for UY Centauri, plotted from ASAS-SN data[1] Observation data Epoch J2000.0 Equinox J2000.0 Constellation Centaurus Right ascension 13h 16m 31.830s[2] Declination −44° 42′ 15.76″[2] Apparent magnitude (V) 6.93 to 9.48[3] Characteristics Evolutionary stage Asymptotic giant branch[4] Spectral type S6/8[5] U−B color index 4.06[6] B−V color index 2.90[6] Variable type SRb[3] Astrometry Radial velocity (Rv) −20.40±1.2[7] km/s Proper motion (μ) RA: −17.492 mas/yr[2] Dec.: 0.351 mas/yr[2] Parallax (π) 1.5075±0.0529 mas[2] Distance 2,160 ± 80 ly (660 ± 20 pc) Details Mass 1.24±0.02[5] M☉ Luminosity 11,884+1,116 −784[8] L☉ Temperature 3,300+100 −300[8] K Metallicity [Fe/H] −0.30±0.15[8] dex Age 3.5±0.1[5] Gyr Other designations UY Cen, CD−44° 8539, GC 17957, HD 115236, HIP 64778, SAO 224021, PPM 318310[9] Database references SIMBAD data

**UY Centauri** is a [variable star](/source/Variable_star) in the southern [constellation](/source/Constellation) of [Centaurus](/source/Centaurus). It ranges from an [apparent visual magnitude](/source/Apparent_visual_magnitude) of 6.93 down to 9.48 with a period of 178.4 days, making it too faint to readily view with the [naked eye](/source/Naked_eye) even at peak brightness.[3] The distance to this star is approximately 2,160 [light years](/source/Light_year) based on [parallax](/source/Stellar_parallax) measurements,[2] although it is drifting closer to the Sun with a [radial velocity](/source/Radial_velocity) of −20 km/s.[7]

In 1911, it was announced that [Williamina Fleming](/source/Williamina_Fleming) had discovered the variability and peculiar spectrum of this star, then known as DM −44° 8539.[10] It was given its [variable star designation](/source/Variable_star_designation), UY Centauri, in 1912.[11] In 1952, [S. Gaposchkin](/source/Sergei_Gaposchkin) listed it as a [semiregular variable](/source/Semiregular_variable_star) with a period of 114.6 days and a [class](/source/Stellar_classification) of K5p.[12] [K. G. Henize](/source/Karl_Gordon_Henize) included it in a list of candidate [S stars](/source/S-type_star) below declination −25°, although noting it showed unusual spectral features.[13] In 1971, UY Cen was named the prototype of SC stars, a rare group with spectra that lie between S- and [C-type stars](/source/Carbon_star).[14]

This is an [evolved](/source/Stellar_evolution) star on the [asymptotic giant branch](/source/Asymptotic_giant_branch) that is shedding mass at an estimated rate of 1.70×10−7 *M*☉·yr−1.[4] The ratio of carbon to oxygen isotopes in the [stellar atmosphere](/source/Stellar_atmosphere) is almost exactly 1.[8] At this stage, it is expected that most of these expelled atoms become locked up in carbon monoxide gas, preventing further dust formation. However, in 2002, this star was observed to undergo a steep decline in luminosity, dropping by two magnitudes. This was interpreted as an episode of circumstellar dust formation. It may be an indication that UY Cen is starting to evolve away from the SC phase.[15]

## References

1. **[^](#cite_ref-ASAS-SN_1-0)** ["ASAS-SN Variable Stars Database"](https://asas-sn.osu.edu/variables/lookup). *ASAS-SN Variable Stars Database*. ASAS-SN. Retrieved 12 October 2024.

1. ^ [***a***](#cite_ref-Gaia_EDR3_2-0) [***b***](#cite_ref-Gaia_EDR3_2-1) [***c***](#cite_ref-Gaia_EDR3_2-2) [***d***](#cite_ref-Gaia_EDR3_2-3) [***e***](#cite_ref-Gaia_EDR3_2-4) [Brown, A. G. A.](/source/Anthony_Brown_(scientist)); et al. (Gaia collaboration) (2021). ["*Gaia* Early Data Release 3: Summary of the contents and survey properties"](https://doi.org/10.1051%2F0004-6361%2F202039657). *[Astronomy & Astrophysics](/source/Astronomy_%26_Astrophysics)*. **649**: A1. [arXiv](/source/ArXiv_(identifier)):[2012.01533](https://arxiv.org/abs/2012.01533). [Bibcode](/source/Bibcode_(identifier)):[2021A&A...649A...1G](https://ui.adsabs.harvard.edu/abs/2021A&A...649A...1G). [doi](/source/Doi_(identifier)):[10.1051/0004-6361/202039657](https://doi.org/10.1051%2F0004-6361%2F202039657). [S2CID](/source/S2CID_(identifier)) [227254300](https://api.semanticscholar.org/CorpusID:227254300). (Erratum: [doi](/source/Doi_(identifier)):[10.1051/0004-6361/202039657e](https://doi.org/10.1051%2F0004-6361%2F202039657e)). [Gaia EDR3 record for this source](https://vizier.u-strasbg.fr/viz-bin/VizieR-S?Gaia%20EDR3%206088137479477550464) at [VizieR](/source/VizieR).

1. ^ [***a***](#cite_ref-Samus_et_al_2017_3-0) [***b***](#cite_ref-Samus_et_al_2017_3-1) [***c***](#cite_ref-Samus_et_al_2017_3-2) Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", *[Astronomy Reports](/source/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-Guandalini_et_al_2010_4-0) [***b***](#cite_ref-Guandalini_et_al_2010_4-1) Guandalini, R. (April 2010), "Infrared photometry and evolution of mass-losing AGB stars. III. Mass loss rates of MS and S stars", *Astronomy and Astrophysics*, **513**: A4, [arXiv](/source/ArXiv_(identifier)):[1002.2458](https://arxiv.org/abs/1002.2458), [Bibcode](/source/Bibcode_(identifier)):[2010A&A...513A...4G](https://ui.adsabs.harvard.edu/abs/2010A&A...513A...4G), [doi](/source/Doi_(identifier)):[10.1051/0004-6361/200911764](https://doi.org/10.1051%2F0004-6361%2F200911764), [S2CID](/source/S2CID_(identifier)) [119193286](https://api.semanticscholar.org/CorpusID:119193286).

1. ^ [***a***](#cite_ref-Borisov_et_al_2023_5-0) [***b***](#cite_ref-Borisov_et_al_2023_5-1) [***c***](#cite_ref-Borisov_et_al_2023_5-2) Borisov, Sviatoslav B.; et al. (May 1, 2023), "New Generation Stellar Spectral Libraries in the Optical and Near-infrared. I. The Recalibrated UVES-POP Library for Stellar Population Synthesis*", *The Astrophysical Journal Supplement Series*, **266** (1): 11, [arXiv](/source/ArXiv_(identifier)):[2211.09130](https://arxiv.org/abs/2211.09130), [Bibcode](/source/Bibcode_(identifier)):[2023ApJS..266...11B](https://ui.adsabs.harvard.edu/abs/2023ApJS..266...11B), [doi](/source/Doi_(identifier)):[10.3847/1538-4365/acc321](https://doi.org/10.3847%2F1538-4365%2Facc321), [ISSN](/source/ISSN_(identifier)) [0067-0049](https://search.worldcat.org/issn/0067-0049).

1. ^ [***a***](#cite_ref-Ducati_2002_6-0) [***b***](#cite_ref-Ducati_2002_6-1) Ducati, J. R. (2002), "Catalogue of Stellar Photometry in Johnson's 11-color system.", *VizieR Online Data Catalog*, CDS/ADC Collection of Electronic Catalogues, **2237**, [Bibcode](/source/Bibcode_(identifier)):[2002yCat.2237....0D](https://ui.adsabs.harvard.edu/abs/2002yCat.2237....0D).

1. ^ [***a***](#cite_ref-Gontcharov_2006_7-0) [***b***](#cite_ref-Gontcharov_2006_7-1) 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-Shetye_et_al_2021_8-0) [***b***](#cite_ref-Shetye_et_al_2021_8-1) [***c***](#cite_ref-Shetye_et_al_2021_8-2) [***d***](#cite_ref-Shetye_et_al_2021_8-3) Shetye, Shreeya; et al. (June 2021), "S stars and s-process in the Gaia era. II. Constraining the luminosity of the third dredge-up with Tc-rich S stars", *Astronomy & Astrophysics*, **650**, id. A118, [arXiv](/source/ArXiv_(identifier)):[2104.03161](https://arxiv.org/abs/2104.03161), [Bibcode](/source/Bibcode_(identifier)):[2021A&A...650A.118S](https://ui.adsabs.harvard.edu/abs/2021A&A...650A.118S), [doi](/source/Doi_(identifier)):[10.1051/0004-6361/202040207](https://doi.org/10.1051%2F0004-6361%2F202040207).

1. **[^](#cite_ref-SIMBAD_9-0)** ["UY Cen"](http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=UY+Cen), *[SIMBAD](/source/SIMBAD)*, [Centre de données astronomiques de Strasbourg](/source/Centre_de_donn%C3%A9es_astronomiques_de_Strasbourg), retrieved 2024-10-08.

1. **[^](#cite_ref-Fleming_Pickering_1911_10-0)** Fleming, Williamina; Pickering, Edward C. (September 1911), "Stars Having Peculiar Spectra. 31 New Variable Stars", *Harvard College Observatory Circular*, **167**: 1–3, [Bibcode](/source/Bibcode_(identifier)):[1911HarCi.167....1F](https://ui.adsabs.harvard.edu/abs/1911HarCi.167....1F).

1. **[^](#cite_ref-Duner1912_11-0)** Dunér; Hartwig; Müller (June 1912). ["Benennung von neu entdeckten veränderlichen Sternen"](https://articles.adsabs.harvard.edu/pdf/1912AN....191..341.). *Astronomische Nachrichten*. **191** (19): 341–358. [Bibcode](/source/Bibcode_(identifier)):[1912AN....191..341.](https://ui.adsabs.harvard.edu/abs/1912AN....191..341.). [doi](/source/Doi_(identifier)):[10.1002/asna.19121911902](https://doi.org/10.1002%2Fasna.19121911902). Retrieved 21 December 2024.

1. **[^](#cite_ref-Gaposchkin_1952_12-0)** Gaposchkin, Sergei (1952), "Variable stars in Milton field 40", *Annals of Harvard College Observatory*, **115**: 181–188, [Bibcode](/source/Bibcode_(identifier)):[1952AnHar.115..181G](https://ui.adsabs.harvard.edu/abs/1952AnHar.115..181G).

1. **[^](#cite_ref-Henize_1960_13-0)** Henize, K. G. (November 1960), "S stars south of declination -25deg", *Astronomical Journal*, **65**: 491, [Bibcode](/source/Bibcode_(identifier)):[1960AJ.....65..491H](https://ui.adsabs.harvard.edu/abs/1960AJ.....65..491H), [doi](/source/Doi_(identifier)):[10.1086/108296](https://doi.org/10.1086%2F108296).

1. **[^](#cite_ref-Catchpole_Feast_1971_14-0)** Catchpole, R. M.; Feast, M. W. (1971), "Spectroscopic observations of SC stars", *Monthly Notices of the Royal Astronomical Society*, **154** (2): 197, [Bibcode](/source/Bibcode_(identifier)):[1971MNRAS.154..197C](https://ui.adsabs.harvard.edu/abs/1971MNRAS.154..197C), [doi](/source/Doi_(identifier)):[10.1093/mnras/154.2.197](https://doi.org/10.1093%2Fmnras%2F154.2.197).

1. **[^](#cite_ref-Steinfadt_et_al_2005_15-0)** Steinfadt, Justin D. R.; et al. (September 2005), "A Unique Dust Formation Episode in the SC-Type Star UY Centauri", *The Publications of the Astronomical Society of the Pacific*, **117** (835): 950–954, [arXiv](/source/ArXiv_(identifier)):[astro-ph/0506505](https://arxiv.org/abs/astro-ph/0506505), [Bibcode](/source/Bibcode_(identifier)):[2005PASP..117..950S](https://ui.adsabs.harvard.edu/abs/2005PASP..117..950S), [doi](/source/Doi_(identifier)):[10.1086/432848](https://doi.org/10.1086%2F432848).

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 [UY Centauri](https://en.wikipedia.org/wiki/UY_Centauri) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/UY_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.