HD 57821

HD 57821 is a single[9] star in the southern constellation of Canis Major. It has a blue-white hue and is faintly visible to the naked eye with an apparent visual magnitude of 4.94.[2] Based on parallax measurements, the distance to this object is approximately 480 light years. It is drifting further away with a radial velocity of +33 km/s, having come to within 71 light-years some 4.3 million years ago.[2]

HD 57821
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Canis Major
Right ascension 07h 22m 13.52901s[1]
Declination −19° 00′ 59.7646″[1]
Apparent magnitude (V) 4.94[2]
Characteristics
Evolutionary stage Main sequence[3]
Spectral type B5 II/III[4] or B7 IV[5]
B−V color index −0.039±0.024[2]
Astrometry
Radial velocity (Rv)+32.9±1.6[2] km/s
Proper motion (μ) RA: −1.69[1] mas/yr
Dec.: +6.91[1] mas/yr
Parallax (π)6.78 ± 0.26[1] mas
Distance480 ± 20 ly
(147 ± 6 pc)
Absolute magnitude (MV)−0.90[2]
Details
Mass4.12±0.08[3] M☉
Radius4.7[6] R☉
Luminosity489+43
−40[3] L☉
Temperature12,445±86[3] K
Rotational velocity (v sin i)116[3] km/s
Age291[7] Myr
Other designations
BD−18°1806, FK5 2570, HD 57821, HIP 35727, HR 2812, SAO 152776[8]
Database references
SIMBADdata

The stellar classification of this star is B5 II/III,[4] which matches the spectrum of a giant/bright giant although stellar models suggest it may still be on the main sequence.[3] It has over four[3] times the mass of the Sun and is 291[7] million years old. The star has a high rate of spin, showing a projected rotational velocity of 116 km/s.[3] It is radiating around 489[3] times the luminosity of the Sun from its photosphere at an effective temperature of 12,445 K.[3]

References
  1. 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. 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.
  3. Zorec, J.; Royer, F. (January 2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics, 537: A120, arXiv:1201.2052, Bibcode:2012A&A...537A.120Z, doi:10.1051/0004-6361/201117691.
  4. Houk, Nancy; Smith-Moore, M. (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, 4, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1988mcts.book.....H.
  5. Cowley, A. (November 1972), "Spectral classification of the bright B8 stars", Astronomical Journal, 77: 750–755, Bibcode:1972AJ.....77..750C, doi:10.1086/111348.
  6. Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics (Third ed.), 367 (2): 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451
  7. Gontcharov, G. A. (November 2012), "Spatial distribution and kinematics of OB stars", Astronomy Letters, 38 (11): 694–706, arXiv:1606.09028, Bibcode:2012AstL...38..694G, doi:10.1134/S1063773712110035.
  8. "HD 57821". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-01-18.
  9. 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.
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