Alpha Lupi

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Alpha Lupi
Diagram showing star positions and boundaries of the Lupus constellation and its surroundings
Cercle rouge 100%.svg

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]
Characteristics
Spectral type B1.5 III[3]
U−B color index –0.88[2]
B−V color index –0.20[2]
Variable type Beta Cephei
Astrometry
Radial velocity (Rv) +5.4 ± 0.6[4] km/s
Proper motion (μ) RA: −20.94[1] mas/yr
Dec.: −23.67[1] mas/yr
Parallax (π) 7.02 ± 0.17[1] mas
Distance 460 ± 10 ly
(142 ± 3 pc)
Absolute magnitude (MV) −4.3[5]
Details
Mass 10.1 ± 1.0[6] M
Luminosity 25,000[5] L
Surface gravity (log g) 3.46[5] cgs
Temperature 21,820 ± 2,160[7] K
Metallicity [Fe/H] 0.04[8] dex
Rotational velocity (v sin i) 16[4] km/s
Age 16–20[4] Myr
Other designations
CD-46 9501, FK5 541, HD 129056, HIP 71860, HR 5469, SAO 225128.[9]

Alpha Lupi (α Lupi, α Lup) is the brightest star in the southern constellation of Lupus. According to the Bortle Dark-Sky Scale, the apparent visual magnitude of 2.3[2] makes it readily visible to the naked eye. Based upon parallax measurements made during the Hipparcos mission,[10] the star is located at a distance of around 460 light-years (140 parsecs) from Earth.[1]

Alpha Lupi is a giant star with a stellar classification of B1.5 III.[3] It has about ten times the mass of the Sun[6] but is radiating 25,000[5] times the Sun's luminosity. The outer atmosphere has an effective temperature of 21,820 K,[7] which gives it the blue-white glow of a B-type star. In 1956 it was identified as a Beta Cephei variable,[11] which means it undergoes periodic changes in luminosity because of pulsations in the atmosphere. The variability period is 0.29585 days,[8] or just over 7 hours, 6 minutes. The magnitude varies by about 0.03, or about 3% of the total luminosity. A small star situated near Alpha Lupi may just be an optical companion.

This star 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.[5] 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.[4]

Etymology[edit]

In Chinese, 騎官 (Qí Guān), meaning Imperial Guards, refers to an asterism consisting of α Lupi, γ Lupi, δ Lupi, κ Centauri, β Lupi, λ Lupi, ε Lupi, μ Lup, π Lupi, and ο Lupi .[12] Consequently, α Lupi itself is known as 騎官十 (Qí Guān shí, English: the Tenth Star of Imperial Guards.).[13]

R. H. Allen had opinion that this star was listed it in the Chinese asterism Yang Mun or Men(南門), meaning "the South Gate", in his work Star-Names and their Meanings.[14] But in Chinese astronomy, 南門 is located in Horn mansion and consisted by α and ε Centauri. Yang Mun was translated in Pinyin as 陽門, meaning "the Yang Gate", refers to the asterism in Neck mansion, containing the stars in Centaurus.[15] Allen also suggested that the Babylonian name for the star was "Kakkab Su-gub Gud-Elim" (Star Left Hand of the Horned Bull).[14]

References[edit]

  1. ^ a b c d e f 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. 
  2. ^ a b c d Johnson, H. L. et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory 4 (99), Bibcode:1966CoLPL...4...99J 
  3. ^ a b 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:1969ApJ...157..313H, doi:10.1086/150069 
  4. ^ 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 
  5. ^ a b c d e 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 
  6. ^ a b 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 
  7. ^ a b Sokolov, N. A. (May 1995), "The determination of T_eff_ of B, A and F main sequence stars from the continuum between 3200 A and 3600 A", Astronomy and Astrophysics Supplement 110: 553–564, Bibcode:1995A&AS..110..553S 
  8. ^ a b 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 
  9. ^ "V* alf Lup -- Variable Star of beta Cep type", SIMBAD (Centre de Données astronomiques de Strasbourg), retrieved 2009-10-26 
  10. ^ Perryman, M. A. C. et al. (April 1997), "The HIPPARCOS Catalogue", Astronomy & Astrophysics 323: L49–L52, Bibcode:1997A&A...323L..49P 
  11. ^ 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 116: 10–24, Bibcode:1956MNRAS.116...10P 
  12. ^ (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.
  13. ^ (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.]
  14. ^ a b Allen, R. H. (1963). Star Names: Their Lore and Meaning (Reprint ed.). New York, NY: Dover Publications Inc. p. 279. ISBN 0-486-21079-0. 
  15. ^ Allen transliterated 南門 as Nan Mun in Centaurus.
    Allen, R. H. (1963). Star Names: Their Lore and Meaning. p. 153. 

See also[edit]