# Alpha Lupi

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Star in the constellation Lupus

Alpha Lupi Location of α Lupi (circled) Observation data Epoch J2000 Equinox J2000 Constellation Lupus Right ascension 14h 41m 55.75579s[1] Declination –47° 23′ 17.5155″[1] Apparent magnitude (V) 2.30[2] (2.29 - 2.34[3]) Characteristics Spectral type B1.5 III[4] U−B color index −0.88[2] B−V color index −0.20[2] Variable type β Cep[3] Astrometry Radial velocity (Rv) +5.4±0.6[5] km/s Proper motion (μ) RA: −20.94[1] mas/yr Dec.: −23.67[1] mas/yr Parallax (π) 7.02±0.17 mas[1] Distance 460 ± 10 ly (142 ± 3 pc) Absolute magnitude (MV) −4.3[6] Details Mass 10.1±1.0[7] M☉ Radius 7.46 ± 0.17[8][a] R☉ Luminosity 18,200+860 −820[8] L☉ Surface gravity (log g) 3.46[6] cgs Temperature 24,550[8] K Metallicity [Fe/H] 0.04[9] dex Rotational velocity (v sin i) 9.5[8] km/s Age 16–20[5] Myr Other designations Uridim, α Lup, CD−46°9501, FK5 541, HD 129056, HIP 71860, HR 5469, SAO 225128[10] Database references SIMBAD data

**Alpha Lupi** (α Lupi, α Lup), also named **Uridim**,[11] is a [blue giant](/source/Blue_giant) star, and the brightest [star](/source/Star) in the southern [constellation](/source/Constellation) of [Lupus](/source/Lupus_(constellation)). According to the [Bortle Dark-Sky Scale](/source/Bortle_Dark-Sky_Scale), its [apparent visual magnitude](/source/Apparent_visual_magnitude) of 2.3[2] makes it readily visible to the naked eye even from highly light-polluted locales. Based upon [parallax](/source/Parallax) measurements made during the [Hipparcos](/source/Hipparcos) mission,[12] the star is around 460 [light-years](/source/Light-year) (140 [parsecs](/source/Parsec)) from the [Solar System](/source/Solar_System).[1] It is one of the nearest [supernova](/source/Supernova) candidates.[13]

## Visibility

Visible from the [Southern Hemisphere](/source/Southern_Hemisphere) for much of the year, it can also be viewed for a shorter season from the [northern tropics](/source/Tropics) and from parts of the [northern subtropical](/source/Subtropics) latitudes.

## Nomenclature

*α Lupi* ([Latinised](/source/Latinisation_of_names) to *Alpha Lupi*) is the star's [Bayer designation](/source/Bayer_designation).

In [Chinese](/source/Chinese_astronomy), *Kekouan* 騎官 (*Qí Guān*), meaning *[Imperial Guards](/source/Root_(Chinese_constellation))*, refers to an asterism consisting of α Lupi, [γ Lupi](/source/Gamma_Lupi), [δ Lupi](/source/Delta_Lupi), [κ Centauri](/source/Kappa_Centauri), [β Lupi](/source/Beta_Lupi), [λ Lupi](/source/Lambda_Lupi), [ε Lupi](/source/Epsilon_Lupi), [μ Lup](/source/Mu_Lupi), [π Lupi](/source/Pi_Lupi), and [ο Lupi](/source/Omicron_Lupi).[14] Consequently, the [Chinese name](/source/Chinese_star_names) for α Lupi itself is 騎官十 (*Qí Guān shí*, English: the Tenth Star of Imperial Guards.).[15]

[R. H. Allen](/source/Richard_Hinckley_Allen) described this star as having the Chinese name *Yang Mun* or *Men* (南門), meaning "the South Gate", in his work *[Star-Names and their Meanings](/source/Star_Names%3A_Their_Lore_and_Meaning)*.[16] In Chinese astronomy, 南門 is located in *[Horn](/source/Horn_(Chinese_constellation))* mansion and consisted of [α](/source/Alpha_Centauri) and [ε](/source/Epsilon_Centauri) Centauri. It was referred to as *Yang Mun*, meaning "the south Gate". Allen also suggested that the Babylonian name for the star was "Kakkab Su-gub Gud-Elim" (Star Left Hand of the Horned Bull).[16]

The [Sumerian](/source/Sumerian_language) name for the constellation Lupus was UR.IDIM, later alternatively written *[Uridimmu](/source/Uridimmu)* in the [Akkadian language](/source/Akkadian_language). The [IAU Working Group on Star Names](/source/IAU_Working_Group_on_Star_Names) approved the name Uridim for this star on 12 September 2024 and it is now so entered in the IAU Catalog of Star Names.[11]

## Characteristics

A [light curve](/source/Light_curve) for Alpha Lupi, plotted from *[Hipparcos](/source/Hipparcos)* data[17]

Alpha Lupi is a [giant star](/source/Blue_giant) with a [stellar classification](/source/Stellar_classification) of B1.5 III.[4] It has about ten times the mass of the Sun[7] yet is radiating 18,000 times the Sun's luminosity. The [outer atmosphere](/source/Stellar_atmosphere) has an [effective temperature](/source/Effective_temperature) of 24,550 K,[8] which gives it the blue-white glow of a [B-type star](/source/B-type_star). In 1956 it was identified as a [Beta Cephei variable](/source/Beta_Cephei_variable) by [Bernard Pagel](/source/Bernard_Pagel) and colleagues,[18] which means it undergoes periodic changes in luminosity because of pulsations in the atmosphere. The variability period is 0.29585 days,[9] or just over 7 hours, 6 minutes. The magnitude varies by about 0.05 magnitudes, or about 5% of its brightness. A 14th magnitude star situated 26" from Alpha Lupi is listed as a companion in double star catalogues.[19]

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.[6] This is a gravitationally unbound stellar association with an estimated age of 16–20 million years. The association is also the source of a bubble of hot gas that contains the Sun, known as the [Local Bubble](/source/Local_Bubble).[5]

## Notes

1. **[^](#cite_ref-radius_9-0)** Applying the [Stefan–Boltzmann law](/source/Stefan%E2%80%93Boltzmann_law) with a nominal [solar](/source/Sun) [effective temperature](/source/Effective_temperature) of 5,772 [K](/source/Kelvin): 1. ( 5 , 772 24 , 550 ) 4 ⋅ 10 4.26 = 7.46 R ⊙ {\displaystyle {\sqrt {{\biggl (}{\frac {5,772}{24,550}}{\biggr )}^{4}\cdot 10^{4.26}}}=7.46\ 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) [***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_2-0) [***b***](#cite_ref-clpl4_2-1) [***c***](#cite_ref-clpl4_2-2) [***d***](#cite_ref-clpl4_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)

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1. ^ [***a***](#cite_ref-apj157_4-0) [***b***](#cite_ref-apj157_4-1) Hiltner, W. A.; Garrison, R. F.; Schild, R. E. (July 1969), "MK Spectral Types for Bright Southern OB Stars", *Astrophysical Journal*, **157**: 313–326, [Bibcode](/source/Bibcode_(identifier)):[1969ApJ...157..313H](https://ui.adsabs.harvard.edu/abs/1969ApJ...157..313H), [doi](/source/Doi_(identifier)):[10.1086/150069](https://doi.org/10.1086%2F150069)

1. ^ [***a***](#cite_ref-aaa448_5-0) [***b***](#cite_ref-aaa448_5-1) [***c***](#cite_ref-aaa448_5-2) Jilinski, E.; et al. (March 2006), "Radial velocity measurements of B stars in the Scorpius–Centaurus association", *Astronomy and Astrophysics*, **448** (3): 1001–1006, [arXiv](/source/ArXiv_(identifier)):[astro-ph/0601643](https://arxiv.org/abs/astro-ph/0601643), [Bibcode](/source/Bibcode_(identifier)):[2006A&A...448.1001J](https://ui.adsabs.harvard.edu/abs/2006A&A...448.1001J), [doi](/source/Doi_(identifier)):[10.1051/0004-6361:20041614](https://doi.org/10.1051%2F0004-6361%3A20041614), [S2CID](/source/S2CID_(identifier)) [17818058](https://api.semanticscholar.org/CorpusID:17818058)

1. ^ [***a***](#cite_ref-aaa216_1_44_6-0) [***b***](#cite_ref-aaa216_1_44_6-1) [***c***](#cite_ref-aaa216_1_44_6-2) de Geus, E. J.; de Zeeuw, P. T.; Lub, J. (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. ^ [***a***](#cite_ref-mnras410_1_190_7-0) [***b***](#cite_ref-mnras410_1_190_7-1) Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (January 2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun", *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-Sharma_8-0) [***b***](#cite_ref-Sharma_8-1) [***c***](#cite_ref-Sharma_8-2) [***d***](#cite_ref-Sharma_8-3) [***e***](#cite_ref-Sharma_8-4) Sharma, Awshesh N.; Bedding, Timothy R.; Saio, Hideyuki; White, Timothy R. (2022). ["Pulsating B stars in the Scorpius–Centaurus Association with TESS"](https://doi.org/10.1093%2Fmnras%2Fstac1816). *Monthly Notices of the Royal Astronomical Society*. **515** (1): 828–840. [arXiv](/source/ArXiv_(identifier)):[2203.02582](https://arxiv.org/abs/2203.02582). [Bibcode](/source/Bibcode_(identifier)):[2022MNRAS.515..828S](https://ui.adsabs.harvard.edu/abs/2022MNRAS.515..828S). [doi](/source/Doi_(identifier)):[10.1093/mnras/stac1816](https://doi.org/10.1093%2Fmnras%2Fstac1816).

1. ^ [***a***](#cite_ref-aaa433_10-0) [***b***](#cite_ref-aaa433_10-1) Daszyńska-Daszkiewicz, J.; Niemczura, E. (April 2005), "Metallicity of mono- and multiperiodic β Cephei stars", *Astronomy and Astrophysics*, **433** (3): 1031–1035, [arXiv](/source/ArXiv_(identifier)):[astro-ph/0410442](https://arxiv.org/abs/astro-ph/0410442), [Bibcode](/source/Bibcode_(identifier)):[2005A&A...433.1031D](https://ui.adsabs.harvard.edu/abs/2005A&A...433.1031D), [doi](/source/Doi_(identifier)):[10.1051/0004-6361:20040397](https://doi.org/10.1051%2F0004-6361%3A20040397), [S2CID](/source/S2CID_(identifier)) [119340011](https://api.semanticscholar.org/CorpusID:119340011)

1. **[^](#cite_ref-SIMBAD_11-0)** ["V* alf Lup -- Variable Star of beta Cep type"](http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=V*+alf+Lup), *SIMBAD*, [Centre de Données astronomiques de Strasbourg](/source/Centre_de_Donn%C3%A9es_astronomiques_de_Strasbourg), retrieved 2009-10-26

1. ^ [***a***](#cite_ref-IAU-CSN-new_12-0) [***b***](#cite_ref-IAU-CSN-new_12-1) ["IAU Catalog of Star Names"](https://exopla.net/star-names/modern-iau-star-names/). Retrieved 22 February 2025.

1. **[^](#cite_ref-hipparcos_13-0)** Perryman, M. A. C.; et al. (April 1997), "The HIPPARCOS Catalogue", *Astronomy & Astrophysics*, **323**: L49–L52, [Bibcode](/source/Bibcode_(identifier)):[1997A&A...323L..49P](https://ui.adsabs.harvard.edu/abs/1997A&A...323L..49P)

1. **[^](#cite_ref-Firestone2014_14-0)** Firestone, R. B. (July 2014), ["Observation of 23 Supernovae That Exploded <300 pc from Earth during the past 300 kyr"](https://zenodo.org/record/895414), *The Astrophysical Journal*, **789** (1): 11, [Bibcode](/source/Bibcode_(identifier)):[2014ApJ...789...29F](https://ui.adsabs.harvard.edu/abs/2014ApJ...789...29F), [doi](/source/Doi_(identifier)):[10.1088/0004-637X/789/1/29](https://doi.org/10.1088%2F0004-637X%2F789%2F1%2F29), [S2CID](/source/S2CID_(identifier)) [122871106](https://api.semanticscholar.org/CorpusID:122871106), 29

1. **[^](#cite_ref-zh_15-0)** (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-hk_16-0)** (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. ^ [***a***](#cite_ref-allen_17-0) [***b***](#cite_ref-allen_17-1) [Allen, R. H.](/source/Richard_Hinckley_Allen) (1963), [*Star Names: Their Lore and Meaning*](/source/Star_Names%3A_Their_Lore_and_Meaning) (Reprint ed.), New York, NY: Dover Publications Inc., p. [279](https://archive.org/details/starnamestheirlo00alle/page/279), [ISBN](/source/ISBN_(identifier)) [0-486-21079-0](https://en.wikipedia.org/wiki/Special:BookSources/0-486-21079-0) {{[citation](https://en.wikipedia.org/wiki/Template:Citation)}}: ISBN / Date incompatibility ([help](https://en.wikipedia.org/wiki/Help:CS1_errors#invalid_isbn_date))

1. **[^](#cite_ref-HIPCurve_18-0)** ["Light Curve"](https://www.cosmos.esa.int/web/hipparcos/java-tools/light-curve). *Hipparcos ESA*. ESA. Retrieved 17 February 2022.

1. **[^](#cite_ref-mnras116_10_19-0)** Pagel, B. E. J. (1956), "Results of a search for bright β Cephei variables in the southern sky", *[Monthly Notices of the Royal Astronomical Society](/source/Monthly_Notices_of_the_Royal_Astronomical_Society)*, **116**: 10–24, [Bibcode](/source/Bibcode_(identifier)):[1956MNRAS.116...10P](https://ui.adsabs.harvard.edu/abs/1956MNRAS.116...10P), [doi](/source/Doi_(identifier)):[10.1093/mnras/116.1.10](https://doi.org/10.1093%2Fmnras%2F116.1.10)

1. **[^](#cite_ref-wds_20-0)** Mason, Brian D.; Wycoff, Gary L.; Hartkopf, William I.; Douglass, Geoffrey G.; Worley, Charles E. (2001), "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog", *The Astronomical Journal*, **122** (6): 3466, [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)

v t e Constellation of Lupus List of stars in Lupus Lupus in Chinese astronomy Stars Bayer α (Uridim) β γ δ ε ζ η θ ι κ λ μ ν1 ν2 ξ ο π ρ σ τ1 τ2 υ φ1 φ2 χ ψ1 ψ2 ω Flamsteed 1 (i) 2 (f) Variable RU EX GG GQ HR II IL IM KT (d) V407 V462 HR 5362 5364 5401 5651 (e) 5724 (k) 5825 (g) 5943 5967 HD 134004 135344 136164 141943 142527 143811 Other Gliese 588 HIP 70849 Lupus-TR-3 SSSPM J1549−3544 WASP-132 Exoplanets GQ Lupi b HIP 70849 b Lupus-TR-3b WASP-178b Star clusters NGC 5749 NGC 5822 NGC 5824 NGC 5927 NGC 5986 Nebulae IC 4406 NGC 5882 Galaxies IC 4444 NGC 5530 NGC 5643 Astronomical events SN 1006 Category

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