Beta Horologii

Beta Horologii, Latinized from β Horologii, is the third-brightest star in the southern constellation of Horologium. It is faintly visible to the naked eye with an apparent visual magnitude of 4.98.[2] Based upon an annual parallax shift of 11.07 mas as seen from Earth,[2] it is located about 295 light years from the Sun. The star is moving away with a radial velocity of +24 km/s.[5]

β Horologii
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Horologium
Right ascension  02h 58m 47.79642s[1]
Declination −64° 04′ 16.6250″[1]
Apparent magnitude (V) 4.979[2]
Characteristics
Spectral type A3/5 III(m)[3]
U−B color index +0.15[4]
B−V color index +0.13[4]
R−I color index +0.05[4]
Astrometry
Radial velocity (Rv)+23.6±2.8[5] km/s
Proper motion (μ) RA: 22.074 ± 0.294[6] mas/yr
Dec.: 5.825 ± 0.287[6] mas/yr
Parallax (π)10.4568 ± 0.1427[6] mas
Distance312 ± 4 ly
(96 ± 1 pc)
Absolute magnitude (MV)+0.20[7]
Details
Radius1.40[8] R☉
Luminosity63[9] L☉
Temperature8,303[9] K
Rotational velocity (v sin i)115[10] km/s
Other designations
β Hor, CPD−64° 215, FK5 2212, GC 3611, HD 18866, HIP 13884, HR 909, SAO 248701, PPM 353263[2]
Database references
SIMBADdata

This is a solitary,[11] A-type giant with a stellar classification of A3/5 III(m).[3] It is a suspected chemically peculiar star of the metallic-line type.[12] Beta Horologii has a relatively high rate of spin with a projected rotational velocity of 115 km/s, giving it an oblate shape with an equatorial bulge that is an estimated 10% wider compared to the polar radius.[10] It has about 1.40[8] times the radius of the Sun and is radiating 63[9] times the Sun's luminosity from its photosphere at an effective temperature of 8,303 K.[9]

References
  1. van Leeuwen, F. (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. "bet hor". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-11-24.
  3. Houk, Nancy (1979), Michigan catalogue of two-dimensional spectral types for the HD stars, 1, Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan, Bibcode:1978mcts.book.....H.
  4. HR 909, database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID V/50. Accessed on line September 18, 2008.
  5. de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, A61.
  6. 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.
  7. 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.
  8. HD 18866, database entry, Catalog of Apparent Diameters and Absolute Radii of Stars (CADARS), 3rd edition, L. E. Pasinetti-Fracassini, L. Pastori, S. Covino, and A. Pozzi, CDS ID II/224. Accessed on line September 18, 2008.
  9. McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x.
  10. van Belle, Gerard T. (March 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.
  11. 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.
  12. Renson, P.; Manfroid, J. (May 2009), "Catalogue of Ap, HgMn and Am stars" (PDF), Astronomy and Astrophysics, 498 (3): 961–966, Bibcode:2009A&A...498..961R, doi:10.1051/0004-6361/200810788.
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