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Sigma Leonis
Observation data
Epoch J2000       Equinox J2000
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  mas [1]
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
SIMBAD data

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. ^ a b c d e Perryman, M. A. C.; et al. (April 1997). "The HIPPARCOS Catalogue". Astronomy & Astrophysics. 323: L49–L52. Bibcode: 1997A&A...323L..49P.
  2. ^ a b 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. ^ a b c 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, arXiv: 1205.5238, Bibcode: 2012MNRAS.424.1925C, doi: 10.1111/j.1365-2966.2012.21317.x, S2CID  119120749
  4. ^ a b 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. ^ a b 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. ^ a b c Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv: 1108.4971, Bibcode: 2012AstL...38..331A, doi: 10.1134/S1063773712050015, S2CID  119257644.
  7. ^ a b c d 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, arXiv: 1501.03154, Bibcode: 2015ApJ...804..146D, doi: 10.1088/0004-637X/804/2/146, S2CID  33401607.
  8. ^ a b c d e 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. arXiv: 0712.3664. Bibcode: 2008MNRAS.385..481L. doi: 10.1111/j.1365-2966.2008.12856.x. S2CID  118320684.
  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, arXiv: astro-ph/0412542, Bibcode: 2005AJ....129.1642F, doi: 10.1086/427855, S2CID  119512018
  10. ^ a b 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. 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, arXiv: 1110.6283, Bibcode: 2012MNRAS.420..757W, doi: 10.1111/j.1365-2966.2011.20090.x, S2CID  14811051.
  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 Archived 2010-08-19 at the Wayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010.
  15. ^ (in Chinese) English-Chinese Glossary of Chinese Star Regions, Asterisms and Star Name Archived 2008-09-24 at the Wayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010.
  16. ^ Allen, Richard Hinckley (1963) [1899], "Leo, the Lion", Star Names, Their Lore and Meaning (Dover ed.), retrieved 2017-08-23.
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