Astronomy:Sigma Leonis

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Short description: Star in the constellation Leo
Sigma Leonis
Observation data
Equinox J2000.0]] (ICRS)
Constellation Leo
Right ascension  11h 21m 08.1943s[1]
Declination +06° 01′ 45.558″[1]
Apparent magnitude (V) 4.046[2]
Characteristics
Spectral type B9.5 Vs[3]
U−B color index –0.12[4]
B−V color index –0.06[4]
Astrometry
Radial velocity (Rv)–5.3[5] km/s
Proper motion (μ) RA: –91.76[1] mas/yr
Dec.: –12.83[1] mas/yr
Parallax (π)15.24 ± 0.81[1] mas
Distance210 ± 10 ly
(66 ± 3 pc)
Absolute magnitude (MV)−0.10[6]
Details
Mass2.76[7] M☉
Radius3.3[8] R☉
Luminosity133[6] L☉
Surface gravity (log g)3.83±0.03[9] cgs
Temperature10,250[8] K
Metallicity [Fe/H]+0.0[8] dex
Rotational velocity (v sin i)70[10] km/s
Age293[7] Myr
Other designations
σ Leo, 77 Leo, BD−06°2437, FK5 427, HD 98664, HIP 55434, HR 4386, SAO 118804[11]
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.[2] 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.[5]

Chini et al. (2012) list this as a single-lined spectroscopic binary system.[3] The visible component has a stellar classification of B9.5 Vs,[3] 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.[12] Sigma Leonis has an estimated 2.76[7] times the mass of the Sun and 3.3[8] times the Sun's radius. It is about 293[7] million years old with a projected rotational velocity of 70 km/s.[10] The star is radiating 133[6] times the Sun's luminosity from its photosphere at an effective temperature of 10,250 K.[8]

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.[13] 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.),[14] representing 西上將 (Xīshǎngjiāng), meaning The First Western General.[15] 西上將 (Xīshǎngjiāng), spelled Shang Tseang by R.H. Allen, means "the Higher General".[16]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 Perryman, M. A. C. (April 1997). "The HIPPARCOS Catalogue". Astronomy & Astrophysics 323: L49–L52. Bibcode: 1997A&A...323L..49P. 
  2. ↑ 2.0 2.1 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. 
  3. ↑ 3.0 3.1 3.2 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 
  4. ↑ 4.0 4.1 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. 
  5. ↑ 5.0 5.1 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. 
  6. ↑ 6.0 6.1 6.2 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A. 
  7. ↑ 7.0 7.1 7.2 7.3 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. 
  8. ↑ 8.0 8.1 8.2 8.3 8.4 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. 
  9. ↑ 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 
  10. ↑ 10.0 10.1 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. 
  11. ↑ "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. 
  12. ↑ 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. 
  13. ↑ (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.
  14. ↑ (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.
  15. ↑ (in Chinese) English-Chinese Glossary of Chinese Star Regions, Asterisms and Star Name , Hong Kong Space Museum. Accessed on line November 23, 2010.
  16. ↑ 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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