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54 Leonis
Observation data
Epoch J2000.0       Equinox
Constellation Leo
54 Leo A
Right ascension 10h 55m 36.80266s [1]
Declination +24° 44′ 59.0440″ [1]
Apparent magnitude (V) 4.477 [2]
54 Leo B
Right ascension 10h 55m 37.24836s [3]
Declination +24° 44′ 56.5478″ [3]
Apparent magnitude (V) 6.29 [4]
Characteristics
54 Leo A
Spectral type A0 V [5]
B−V color index +0.001 [5]
54 Leo B
Spectral type A2 Vn [5]
B−V color index +0.07 [4]
Astrometry
54 Leo A
Radial velocity (Rv)−0.49±0.98 [6] km/s
Proper motion (μ) RA: −78.057 [1]  mas/ yr
Dec.: −16.520 [1]  mas/ yr
Parallax (π)9.8275 ± 0.3537  mas [1]
Distance330 ± 10  ly
(102 ± 4  pc)
Absolute magnitude (MV)–0.29 [7]
54 Leo B
Radial velocity (Rv)1.30±0.92 [6] km/s
Proper motion (μ) RA: −75.374 [3]  mas/ yr
Dec.: −18.595 [3]  mas/ yr
Parallax (π)10.1748 ± 0.0569  mas [3]
Distance321 ± 2  ly
(98.3 ± 0.5  pc)
Details
54 Leo A
Mass2.4+0.44
−0.36 [8]  M☉
Radius2.88 [9]  R☉
Surface gravity (log g)3.5±0.25 [8]  cgs
Temperature9000±500 [8]  K
Rotational velocity (v sin i)185 [10] km/s
Age411+137
−168 [8]  Myr
54 Leo B
Radius2.59 [9]  R☉
Rotational velocity (v sin i)250±20 [9] km/s
Other designations
54 Leo, BD+25 2314, CCDM J10556+2445, HIP 53417, Struve 1487 [11]
54 Leo A: HD 94601, HR 4259, SAO 81583
54 Leo B: HD 94602, HR 4260, SAO 81584
Database references
SIMBAD data

54 Leonis is a binary star [12] system in the zodiac constellation of Leo, located around 321 [3]  light years from the Sun. It is visible to the naked eye as a faint, white-hued star with a combined apparent visual magnitude of 4.30. [13] As of 2017, the pair had an angular separation of 6.60 ″ along a position angle of 113°. [14] They have a physical separation of around 533  AU (79,700  Gm). [9]

The magnitude 4.477 [2] primary, designated component A, is an A-type main-sequence star with a stellar classification of A0 V, [5] which indicates it is generating energy through hydrogen fusion at its core. It has a high rate of spin, showing a projected rotational velocity of 185 km/s. This is giving the star an oblate shape with an equatorial bulge that is an estimated 8% larger than the polar radius. [10] The star is roughly 411 [8] million years old with 2.4 [8] times the mass of the Sun and about 2.88 [9] times the Sun's radius.

The fainter magnitude 6.29 [4] secondary, component B, is a smaller A-type main-sequence star with a class of A2 Vn. [5] The 'n' suffix indicates wide "nebulous" lines due to rapid rotation. It is spinning with an even higher projected rotational velocity of 250 [9] km/s. The star has about 2.59 [9] times the Sun's radius.

Asteroid 729 Watsonia occulted HIP 53417 on March 3, 2013 at 01:48. [15]

References

  1. ^ a b c d e Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv: 1804.09365. Bibcode: 2018A&A...616A...1G. doi: 10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. ^ a b Høg, E.; et al. (2000), "The Tycho-2 catalogue of the 2.5 million brightest stars", Astronomy and Astrophysics, 355: L27, Bibcode: 2000A&A...355L..27H, doi: 10.1888/0333750888/2862.
  3. ^ a b c d e f Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv: 1804.09365. Bibcode: 2018A&A...616A...1G. doi: 10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  4. ^ a b c Fabricius, C.; et al. (2002), "The Tycho double star catalogue", Astronomy and Astrophysics, 384: 180–189, Bibcode: 2002A&A...384..180F, doi: 10.1051/0004-6361:20011822
  5. ^ a b c d e Cowley, A.; et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal, 74: 375–406, Bibcode: 1969AJ.....74..375C, doi: 10.1086/110819.
  6. ^ a b Becker, Juliette C.; et al. (April 2015), "Extracting Radial Velocities of A- and B-type Stars from Echelle Spectrograph Calibration Spectra", The Astrophysical Journal Supplement Series, 217 (2): 13, arXiv: 1503.03874, Bibcode: 2015ApJS..217...29B, doi: 10.1088/0067-0049/217/2/29, S2CID  33968873, 29.
  7. ^ Pizzolato, N.; Maggio, A.; Sciortino, S. (September 2000), "Evolution of X-ray activity of 1-3 Msun late-type stars in early post-main-sequence phases", Astronomy and Astrophysics, 361: 614–628, Bibcode: 2000A&A...361..614P
  8. ^ a b c d e f Gullikson, Kevin; et al. (2016), "The Close Companion Mass-ratio Distribution of Intermediate-mass Stars", The Astronomical Journal, 152 (2): 40, arXiv: 1604.06456, Bibcode: 2016AJ....152...40G, doi: 10.3847/0004-6256/152/2/40, S2CID  119179065.
  9. ^ a b c d e f g Howe, K. S.; Clarke, C. J. (January 2009), "An analysis of v sin (i) correlations in early-type binaries", Monthly Notices of the Royal Astronomical Society, 392 (1): 448–454, Bibcode: 2009MNRAS.392..448H, doi: 10.1111/j.1365-2966.2008.14073.x
  10. ^ a b Belle, G. T. (2012), "Interferometric observations of rapidly rotating stars", The Astronomy and Astrophysics Review, 20 (1): 51, arXiv: 1204.2572, Bibcode: 2012A&ARv..20...51V, doi: 10.1007/s00159-012-0051-2, S2CID  119273474.
  11. ^ "54 Leo". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-02-05.
  12. ^ Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv: 0806.2878, Bibcode: 2008MNRAS.389..869E, doi: 10.1111/j.1365-2966.2008.13596.x, S2CID  14878976.
  13. ^ 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.
  14. ^ Mason, Brian D.; et al. (December 2001), "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog", The Astronomical Journal, 122 (6), U. S. Naval Observatory, Washington D.C.: 3466–3471, Bibcode: 2001AJ....122.3466M, doi: 10.1086/323920.
  15. ^ Pier Paolo Ricci (29 November 2012). Almanacco astronomico 2013 Astronomical almanac 2013. Lulu.com. pp. 322–. ISBN  978-1-291-21157-3.
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