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Kappa Librae
Observation data; Epoch J2000.0 Equinox J2000.0 (ICRS)
Constellation	Libra
Right ascension	15h 41m 56.79858s
Declination	−19° 40′ 43.7745″
Apparent magnitude (V)	4.72
Characteristics
Spectral type	K5 III
U−B color index	+1.94
B−V color index	+1.58
Astrometry
Radial velocity (Rv)	−4.5±1.5 km/s
Proper motion (μ)	RA: −32.06 mas/yr ; Dec.: −103.15 mas/yr
Parallax (π)	10.57 ± 1.40 mas
Distance	approx. 310 ly ; (approx. 90 pc)
Absolute magnitude (MV)	−0.62
Details
Radius	38 R☉
Luminosity	296 L☉
Temperature	3,930 K
Other designations
	κ Lib, 43 Lib, BD−19° 4188, FK5 1413, HD 139997, HIP 76880, HR 5838, SAO 159442
Database references
SIMBAD	data

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. The annual parallax shift of 10.57 mas^[1] indicates it is roughly 310 light years away. It is positioned 0.02 degrees south of the ecliptic.

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

^ ^a ^b ^c ^d ^e ^f 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, S2CID 18759600.
^ ^a ^b ^c ^d Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99): 99, Bibcode:1966CoLPL...4...99J.
^ ^a ^b Houk, Nancy; Smith-Moore, M. (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 4, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1988mcts.book.....H.
^ 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, S2CID 59451347, A61.
^ 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.
^ ^a ^b Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, vol. 1 (3rd ed.), Birkhäuser, ISBN 3-540-29692-1. The radius (R_*) is given by:
${\begin{aligned}2\cdot R_{*}&={\frac {(94.6\cdot 3.71\cdot 10^{-3})\ {\text{AU}}}{0.0046491\ {\text{AU}}/R_{\bigodot }}}\\&\approx 75.5\cdot R_{\bigodot }\end{aligned}}$
^ ^a ^b ^c 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, S2CID 118665352.
^ "kap Lib". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-01-30.{{cite web}}: CS1 maint: postscript (link)
^ Makarov, V. V.; Kaplan, G. H. (May 2005), "Statistical Constraints for Astrometric Binaries with Nonlinear Motion" (PDF), The Astronomical Journal, 129 (5): 2420–2427, Bibcode:2005AJ....129.2420M, doi:10.1086/429590, archived from the original on September 24, 2017.
^ Samus, N. N.; Durlevich, O. V.; et al. (2004), "Combined General Catalogue of Variable Stars (GCVS4.2)", Vizier Online Data Catalog, Bibcode:2004yCat.2250....0S.
^ Richichi, A.; et al. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics, 431 (2): 773–777, Bibcode:2005A&A...431..773R, doi:10.1051/0004-6361:20042039.
^ Ian Ridpath's Startales - Libra the Scales