Epoch J2000 Equinox J2000
|Right ascension||14h 58m 31.92536s|
|Declination||−43° 08′ 02.2699″|
|Apparent magnitude (V)||2.68|
|Spectral type||B2 III|
|U−B color index||−0.902|
|B−V color index||−0.226|
|Variable type||β Cep|
|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|
|Mass||8.8 ± 0.2 M☉|
|Surface gravity (log g)||3.76 cgs|
|Metallicity [Fe/H]||−0.35 ± 0.11 dex|
|Rotational velocity (v sin i)||92 km/s|
|Age||24.6 ± 2.7 Myr|
Beta Lupi (β Lupi, β Lup) is a star in the southern constellation of Lupus. It has an apparent visual magnitude of 2.7, 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.
The stellar classification of B2 III indicates this is a giant star. The effective temperature of the star's outer envelope is 24,090 K, giving it the blue-white hue of a B-type star. With an age of around 25 million years, 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 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.
This is a multi-period Beta Cephei variable with a dominant oscillation period of 0.232 days. 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. Beta Lupi has a high proper motion of more than 50 mas per year, suggesting a significant transverse velocity.
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. Consequently, β Lupi itself is known as 騎官四 (Qí Guān sì, English: the Fourth Star of Imperial Guards.). From this Chinese name, the name Ke Kwan was appeared.
- 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
- Wielen, R. et al. (1999), Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions (35), Astronomisches Rechen-Institut Heidelberg, Bibcode:1999VeARI..35....1W
- 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
- 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
- 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
- de Geus, P. T.; de Zeeuw; 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
- 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
- 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: 601–605, Bibcode:1979MNRAS.189..601U
- 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, Bibcode:2009A&A...501..297Z, doi:10.1051/0004-6361/200811147
- "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, retrieved 2012-01-16
- Kaler, James B. (2007), "Beta Lupi", Stars (University of Illinois), 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
- (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.
- (Chinese) 香港太空館 - 研究資源 - 亮星中英對照表, Hong Kong Space Museum. Accessed on line November 23, 2010.]
- Richard Hinckley Allen: Star Names — Their Lore and Meaning: Lupus