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Beta Lupi
	Location of β Lupus (circled)
Observation data; Epoch J2000 Equinox J2000
Constellation	Lupus
Right ascension	14h 58m 31.92536s
Declination	−43° 08′ 02.2699″
Apparent magnitude (V)	2.68
Characteristics
Spectral type	B2 III
U−B color index	−0.902
B−V color index	−0.226
Variable type	β Cep
Astrometry
Radial velocity (Rv)	+0.1 ± 1.0 km/s
Proper motion (μ)	RA: −35.78 mas/yr ; Dec.: −39.83 mas/yr
Parallax (π)	8.52 ± 0.18 mas
Distance	383 ± 8 ly ; (117 ± 2 pc)
Absolute magnitude (MV)	−3.3
Details
Mass	8.8±0.2 M☉
Radius	6.6 R☉
Luminosity	10,000 L☉
Surface gravity (log g)	3.76 cgs
Temperature	24,090 K
Metallicity [Fe/H]	−0.35±0.11 dex
Rotational velocity (v sin i)	92 km/s
Age	24.6±2.7 Myr
Other designations
	Kekouan, β Lup, CD−42° 9853, FK5 552, HD 132058, HIP 73273, HR 5571, SAO 225335
Database references
SIMBAD	data

Beta Lupi (Latinized from β Lupi) or Kekouan (/ˈkɛkwɑːn/), is a star in the southern constellation of Lupus. It has an apparent visual magnitude of 2.7,^[2] making it readily visible to the naked eye. Based upon parallax measurements, this star is located at a distance of about 383 light-years (117 parsecs) from Earth.^[2]

Properties

The stellar classification of B2 III indicates this is a giant star.^[3] The effective temperature of the star's outer envelope is 24,090 K,^[9] giving it the blue-white hue of a B-type star.^[11] With an age of around 25 million years,^[7] it is near the end of its hydrogen phase, where hydrogen is fused into the element helium, and transferring into a red supergiant star. At about 8.8^[7] solar masses, it may have enough mass to end its life as a Type II supernova, but there is the possibility of Beta Lupi becoming a white dwarf.^[12]

This is a multi-period Beta Cephei variable with a dominant oscillation period of 0.232 days.^[5] It is a proper motion member of the Upper Centaurus–Lupus sub-group in the Scorpius–Centaurus OB association, the nearest such co-moving association of massive stars to the Sun.^[6] Beta Lupi has a high proper motion of more than 50 mas per year, suggesting a significant transverse velocity.^[13]

It is positioned about 1.3° SSW of the supernova remnant SN 1006.^[14]

Name

In Chinese, 騎官 (Qí Guān), meaning Imperial Guards, refers to an asterism consisting of β Lupi, γ Lupi, δ Lupi, κ Centauri, λ Lupi, ε Lupi, μ Lup, π Lupi, ο Lupi and α Lupi.^[15] Consequently, the Chinese name for β Lupi itself is 騎官四 (Qí Guān sì, English: the Fourth Star of Imperial Guards.).^[16] From the French rendering of this Chinese name derives the traditional European name Kekouan (Ke Kwan).^[17]

References

^ ^a ^b ^c ^d ^e van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600
^ ^a ^b ^c Wielen, R.; et al. (1999), "Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions", Veroeffentlichungen des Astronomischen Rechen-Instituts Heidelberg, 35 (35), Astronomisches Rechen-Institut Heidelberg: 1, Bibcode:1999VeARI..35....1W
^ ^a ^b ^c ^d 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:astro-ph/0601643, Bibcode:2006A&A...448.1001J, doi:10.1051/0004-6361:20041614, S2CID 17818058
^ ^a ^b Gutierrez-Moreno, Adelina; Moreno, Hugo (June 1968), "A photometric investigation of the Scorpio-Centaurus association", Astrophysical Journal Supplement, 15: 459, Bibcode:1968ApJS...15..459G, doi:10.1086/190168
^ ^a ^b ^c Daszyńska-Daszkiewicz, J.; Niemczura, E. (April 2005), "Metallicity of mono- and multiperiodic β Cephei stars", Astronomy and Astrophysics, 433 (3): 1031–1035, arXiv:astro-ph/0410442, Bibcode:2005A&A...433.1031D, doi:10.1051/0004-6361:20040397, S2CID 119340011
^ ^a ^b ^c ^d 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:1989A&A...216...44D
^ ^a ^b ^c ^d 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:1007.4883, Bibcode:2011MNRAS.410..190T, doi:10.1111/j.1365-2966.2010.17434.x, S2CID 118629873
^ Underhill, A. B.; et al. (November 1979), "Effective temperatures, angular diameters, distances and linear radii for 160 O and B stars", Monthly Notices of the Royal Astronomical Society, 189 (3): 601–605, Bibcode:1979MNRAS.189..601U, doi:10.1093/mnras/189.3.601
^ ^a ^b Zorec, J.; et al. (July 2009), "Fundamental parameters of B supergiants from the BCD system. I. Calibration of the (λ_1, D) parameters into Teff", Astronomy and Astrophysics, 501 (1): 297–320, arXiv:0903.5134, Bibcode:2009A&A...501..297Z, doi:10.1051/0004-6361/200811147, S2CID 14969137
^ "bet Lup -- Variable Star", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2012-01-16
^ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on 2012-03-18, retrieved 2012-01-16
^ Kaler, James B. (2007), "Beta Lupi", Stars, University of Illinois, archived from the original on 2011-07-16, retrieved 2009-07-03
^ Jiménez-Esteban, F. M.; Caballero, J. A.; Solano, E. (January 2011), "Identification of blue high proper motion objects in the Tycho-2 and 2MASS catalogues using Virtual Observatory tools", Astronomy and Astrophysics, 525: A29, arXiv:1009.3466, Bibcode:2011A&A...525A..29J, doi:10.1051/0004-6361/201015223, S2CID 55172549
^ Sinnott, Roger W.; Perryman, Michael A. C. (1997), Millennium Star Atlas, vol. 2, Sky Publishing Corporation and the European Space Agency, p. 929, ISBN 0-933346-83-2.
^ (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 978-986-7332-25-7.
^ (in Chinese) 香港太空館 - 研究資源 - 亮星中英對照表 Archived 2011-01-29 at the Wayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010.]
^ Richard Hinckley Allen: Star Names — Their Lore and Meaning: Lupus