Kappa Librae

Kappa Librae, Latinized from κ Librae, is the Bayer designation for a star system in the zodiac constellation of Libra. Its apparent visual magnitude is 4.72,[2] so it can be seen with the naked eye. Its annual parallax shift is 10.57 mas,[1] indicating it is roughly 310 light years away. It is 0.02 degree south of the ecliptic.

Kappa Librae
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Libra
Right ascension 15h 41m 56.79858s[1]
Declination −19° 40′ 43.7745″[1]
Apparent magnitude (V) 4.72[2]
Characteristics
Spectral type K5 III[3]
U−B color index +1.94[2]
B−V color index +1.58[2]
Astrometry
Radial velocity (Rv)−4.5±1.5[4] km/s
Proper motion (μ) RA: −32.06[1] mas/yr
Dec.: −103.15[1] mas/yr
Parallax (π)10.57 ± 1.40[1] mas
Distanceapprox. 310 ly
(approx. 90 pc)
Absolute magnitude (MV)−0.62[5]
Details
Radius38[6] R☉
Luminosity296[7] L☉
Temperature3,930[7] K
Other designations
κ Lib, 43 Lib, BD−19° 4188, FK5 1413, HD 139997, HIP 76880, HR 5838, SAO 159442.[8]
Database references
SIMBADdata

The star shows acceleration components in its proper motion, indicating with high probability that it is an astrometric binary.[9] The visible component is an evolved K-type giant star with a stellar classification of K5 III.[3] It is a suspected variable star with a brightness that ranges between 4.70 and 4.75.[10] The measured angular diameter is 3.71±0.10 mas,[11] which, at the estimated distance of Kappa Librae, yields a physical size of about 38 times the radius of the Sun.[6] It radiates 296 times the solar luminosity from its outer atmosphere at an effective temperature of 3,930 K.[7]

In Chinese astronomy, Kappa Librae is called 日, Pinyin: Rì, meaning Sun, because this star is marking itself and stand alone in Sun asterism, Room mansion (see : Chinese constellation).[12]

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. Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99), Bibcode:1966CoLPL...4...99J.
  3. 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.
  4. 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.
  5. 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.
  6. Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, 1 (3rd ed.), Birkhäuser, ISBN 3-540-29692-1. The radius (R*) is given by:
  7. 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.
  8. "kap Lib". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-01-30.
  9. Makarov, V. V.; Kaplan, G. H. (May 2005), "Statistical Constraints for Astrometric Binaries with Nonlinear Motion", The Astronomical Journal, 129 (5): 2420–2427, Bibcode:2005AJ....129.2420M, doi:10.1086/429590.
  10. Samus, N. N.; Durlevich, O. V.; et al. (2004), Combined General Catalogue of Variable Stars (GCVS4.2), Bibcode:2004yCat.2250....0S.
  11. Richichi, A.; et al. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics, 431: 773–777, Bibcode:2005A&A...431..773R, doi:10.1051/0004-6361:20042039.
  12. Ian Ridpath's Startales - Libra the Scales
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