Astronomy:Sigma Leonis

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Short description: Star in the constellation Leo
Sigma Leonis
Observation data
Equinox J2000.0]] (ICRS)
Constellation Leo[1]
Right ascension  11h 21m 08.1943s[2]
Declination +06° 01′ 45.558″[2]
Apparent magnitude (V) 4.046[3]
Characteristics
Evolutionary stage main sequence[4]
Spectral type B9.5 Vs[5]
U−B color index −0.12[6]
B−V color index −0.06[6]
Astrometry
Radial velocity (Rv)−5.3[7] km/s
Proper motion (μ) RA: −91.76[2] mas/yr
Dec.: −12.83[2] mas/yr
Parallax (π)15.24 ± 0.81[2] mas
Distance210 ± 10 ly
(66 ± 3 pc)
Absolute magnitude (MV)−0.10[1]
Details
Mass2.76[8] M☉
Radius3.07±0.23[9] R☉
Luminosity133[1] L☉
Surface gravity (log g)3.83±0.03[10] cgs
Temperature11,000±1,000[9] K
Metallicity [Fe/H]+0.0[11] dex
Rotational velocity (v sin i)70[12] km/s
Age293[8] Myr
Other designations
σ Leo, 77 Leo, BD−06°2437, FK5 427, HD 98664, HIP 55434, HR 4386, SAO 118804[13]
Database references
SIMBADdata

Sigma Leonis, Latinized from σ Leonis, is a blue-white hued star in the zodiac constellation Leo that is visible to the naked eye with an apparent visual magnitude of 4.0.[3] Its annual parallax shift of 15.24 mas as seen from Earth implies a distance around 210 light years from the Sun. It is moving closer to the Sun with a radial velocity of –5 km/s.[7]

Chini et al. (2012) list this as a single-lined spectroscopic binary system.[5] The visible component has a stellar classification of B9.5 Vs,[5] indicating it is a B-type main-sequence star. It is a suspected magnetic Ap star that shows an abundance anomaly with the element silicon.[14] Sigma Leonis has an estimated 2.76 times the mass of the Sun[8] and 3.07 times the Sun's radius.[9] It is about 293 million years old[8] with a projected rotational velocity of 70 km/s.[12] The star is radiating 133 times the Sun's luminosity from its photosphere[1] at an effective temperature of 11,000 K.[9]

Name

In Chinese, 太微右垣 (Tài Wēi Yòu Yuán), meaning Right Wall of Supreme Palace Enclosure, refers to an asterism consisting of σ Leonis, β Virginis, ι Leonis, θ Leonis and δ Leonis.[15] Consequently, the Chinese name for σ Leonis itself is 太微右垣二 (Tài Wēi Yòu Yuán èr, English: the Second Star of Right Wall of Supreme Palace Enclosure.),[16] representing 西上將 (Xīshǎngjiāng), meaning The First Western General.[17] 西上將 (Xīshǎngjiāng), spelled Shang Tseang by R.H. Allen, means "the Higher General".[18]

References

  1. ↑ 1.0 1.1 1.2 1.3 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A. 
  2. ↑ 2.0 2.1 2.2 2.3 2.4 Perryman, M. A. C. (April 1997). "The HIPPARCOS Catalogue". Astronomy & Astrophysics 323: L49–L52. Bibcode: 1997A&A...323L..49P. 
  3. ↑ 3.0 3.1 Cousins, A. W. J. (1984). "Standardisation of broad band photometry of equatorial standards". South Africa Astronomical Observatory Circular 8: 59–67. Bibcode: 1984SAAOC...8...59C. 
  4. ↑ Zorec, J.; Royer, F. (2012). "Rotational velocities of A-type stars. IV. Evolution of rotational velocities". Astronomy and Astrophysics 537: A120. doi:10.1051/0004-6361/201117691. Bibcode: 2012A&A...537A.120Z. 
  5. ↑ 5.0 5.1 5.2 Chini, R. et al. (August 2012). "spectroscopic survey on the multiplicity of high-mass stars". Monthly Notices of the Royal Astronomical Society 424 (3): 1925–1929. doi:10.1111/j.1365-2966.2012.21317.x. Bibcode: 2012MNRAS.424.1925C. 
  6. ↑ 6.0 6.1 Johnson, H. L.; Iriarte, B.; Mitchell, R. I.; Wisniewskj, W. Z. (1966). "UBVRIJKL photometry of the bright stars". Communications of the Lunar and Planetary Laboratory 4 (99): 99. Bibcode: 1966CoLPL...4...99J. 
  7. ↑ 7.0 7.1 Wilson, Ralph Elmer (1953). "General Catalogue of Stellar Radial Velocities". Carnegie Institute Washington D.C. Publication (Washington: Carnegie Institution of Washington). Bibcode: 1953GCRV..C......0W. 
  8. ↑ 8.0 8.1 8.2 8.3 David, Trevor J.; Hillenbrand, Lynne A. (2015). "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets". The Astrophysical Journal 804 (2): 146. doi:10.1088/0004-637X/804/2/146. Bibcode: 2015ApJ...804..146D. 
  9. ↑ 9.0 9.1 9.2 9.3 Gordon, Kathryn D.; Gies, Douglas R.; Schaefer, Gail H.; Huber, Daniel; Ireland, Michael (2019). "Angular Sizes, Radii, and Effective Temperatures of B-type Stars from Optical Interferometry with the CHARA Array". The Astrophysical Journal 873 (1): 91. doi:10.3847/1538-4357/ab04b2. Bibcode: 2019ApJ...873...91G. 
  10. ↑ Fitzpatrick, E. L.; Massa, D. (March 2005). "Determining the Physical Properties of the B Stars. II. Calibration of Synthetic Photometry". The Astronomical Journal 129 (3): 1642–1662. doi:10.1086/427855. Bibcode: 2005AJ....129.1642F. 
  11. ↑ Lipski, Ł.; Stȩpień, K. (March 2008). "Effective temperatures of magnetic chemically peculiar stars from full spectral energy distributions". Monthly Notices of the Royal Astronomical Society 385 (1): 481–492. doi:10.1111/j.1365-2966.2008.12856.x. Bibcode: 2008MNRAS.385..481L. 
  12. ↑ 12.0 12.1 Bernacca, P. L.; Perinotto, M. (1970). "A catalogue of stellar rotational velocities". Contributi Osservatorio Astronomico di Padova in Asiago 239 (1): 1. Bibcode: 1970CoAsi.239....1B. 
  13. ↑ "sig Leo -- Star". SIMBAD. Centre de Données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=Sigma+Leonis. Retrieved 2010-06-23. 
  14. ↑ Wraight, K. T. et al. (February 2012). "A photometric study of chemically peculiar stars with the STEREO satellites - I. Magnetic chemically peculiar stars". Monthly Notices of the Royal Astronomical Society 420 (1): 757–772. doi:10.1111/j.1365-2966.2011.20090.x. Bibcode: 2012MNRAS.420..757W. 
  15. ↑ (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.
  16. ↑ (in 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.
  17. ↑ (in Chinese) English-Chinese Glossary of Chinese Star Regions, Asterisms and Star Name , Hong Kong Space Museum. Accessed on line November 23, 2010.
  18. ↑ Allen, Richard Hinckley (1963). "Leo, the Lion". Star Names, Their Lore and Meaning (Dover ed.). https://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Leo*.html. Retrieved 2017-08-23. 



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