Lambda Horologii

λ Horologii, Latinised as Lambda Horologii, is a star in the southern constellation of Horologium. It is a yellow-white hued star that is dimly visible to the naked eye with an apparent visual magnitude of +5.35.^[2] Based upon parallax, this object is located 155 light years distance from the Sun. It is drifting further away with a radial velocity of +28 km/s.^[1] Although Eggleton and Tokovinin (2008) list this as a single star,^[8] according to Kunzli and North (1998) it may be a binary system with a long orbital period.^[9]

Lambda Horologii

Observation data Epoch J2000      Equinox J2000
Constellation	Horologium
Right ascension	02h 24m 53.91034s[1]
Declination	−60° 18′ 43.0170″[1]
Apparent magnitude (V)	+5.35[2]
Characteristics
Spectral type	F2III[3]
B−V color index	+0.39[2]
Astrometry
Radial velocity (Rv)	+28.34±0.41[1] km/s
Proper motion (μ)	RA: −71.892[1] mas/yr Dec.: −131.088[1] mas/yr
Parallax (π)	21.0119±0.1004 mas[1]
Distance	155.2 ± 0.7 ly (47.6 ± 0.2 pc)
Absolute magnitude (MV)	+1.91[4]
Details
Mass	1.76[5] M☉
Radius	2.74+0.11 −0.16[1] R☉
Luminosity	13.3±0.1[1] L☉
Surface gravity (log g)	3.66[6] cgs
Temperature	6,848[5] K
Metallicity [Fe/H]	−0.12[5] dex
Rotational velocity (v sin i)	+140[3] km/s
Age	1.4[5] Gyr
Other designations
λ Hor, CPD−60°199, FK5 84, HD 15233, HIP 11258, HR 714, SAO 248555[7]
Database references
SIMBAD	data

The visible component has a stellar classification of F2III,^[3] matching an evolved star that has, at the age of 1.4 billion years,^[5] become a giant. However, it has just 2.74^[1] times the Sun's radius and shows a high rate of spin with a projected rotational velocity of +140 km/s.^[3] The star has 1.76^[5] times the mass of the Sun and is radiating 13^[1] times the Sun's luminosity from its photosphere at an effective temperature of 6,848 K.^[5]