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,^[3] so it can be seen with the naked eye. The annual parallax shift of 10.57 mas^[2] indicates it is roughly 310 light years away. It is positioned 0.02 degrees south of the ecliptic.

Kappa Librae

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Libra[1]
Right ascension	15h 41m 56.79858s[2]
Declination	−19° 40′ 43.7745″[2]
Apparent magnitude (V)	4.72[3]
Characteristics
Spectral type	K5 III[4]
U−B color index	+1.94[3]
B−V color index	+1.58[3]
Astrometry
Radial velocity (Rv)	−4.5±1.5[5] km/s
Proper motion (μ)	RA: −32.06[2] mas/yr Dec.: −103.15[2] mas/yr
Parallax (π)	10.57±1.40 mas[2]
Distance	approx. 310 ly (approx. 90 pc)
Absolute magnitude (MV)	−0.62[1]
Details
Mass	1.6[6] M☉
Radius	41[7] R☉
Luminosity	388[8] L☉
Surface gravity (log g)	1.35[6] cgs
Temperature	3,955[7] K
Metallicity [Fe/H]	−0.39[6] dex
Other designations
κ Lib, 43 Lib, BD−19°4188, FK5 1413, HD 139997, HIP 76880, HR 5838, SAO 159442[9]
Database references
SIMBAD	data

The star shows acceleration components in its proper motion, indicating with high probability that it is an astrometric binary.^[10] The visible component is an evolved K-type giant star with a stellar classification of K5 III.^[4] It is a suspected variable star with a brightness that ranges between 4.70 and 4.75.^[11] The measured angular diameter is 3.71±0.10 mas,^[12] which, at the estimated distance of Kappa Librae, yields a physical size of about 41 times the radius of the Sun.^[7] It radiates 388 times the solar luminosity^[8] from its outer atmosphere at an effective temperature of 3,955 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).^[13]