Omicron Boötis

Omicron Boötis is a yellow-hued star in the northern constellation of Boötes. Its name is a Bayer designation that is Latinized from ο Boötis, and abbreviated Omicron Boo or ο Boo. With an apparent visual magnitude of +4.60,^[2] it is a fifth magnitude star that is faintly visible to the naked eye. Based upon an annual parallax shift of 12.68 mas as seen from the Earth,^[1] it is located at a distance of approximately 257 light-years (78.9 pc). The star is moving closer to the Sun with a radial velocity of −9 km/s.^[7]

ο Boötis

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Boötes
Right ascension	14h 45m 14.461s[1]
Declination	+16° 57′ 51.40″[1]
Apparent magnitude (V)	+4.60[2]
Characteristics
Evolutionary stage	red clump[3]
Spectral type	G8.5 III[4]
U−B color index	+0.75[2]
B−V color index	+0.98[2]
Astrometry
Radial velocity (Rv)	−9.18[5] km/s
Proper motion (μ)	RA: −59.581 mas/yr[1] Dec.: −52.524 mas/yr[1]
Parallax (π)	12.6814±0.1385 mas[1]
Distance	257 ± 3 ly (78.9 ± 0.9 pc)
Absolute magnitude (MV)	0.70[6]
Details
Mass	2.05[5] M☉
Radius	11[7] R☉
Luminosity	85[5] L☉
Surface gravity (log g)	2.7[7] cgs
Temperature	4,864±25[5] K
Metallicity [Fe/H]	−0.10[7] dex
Rotational velocity (v sin i)	3.6[7] km/s
Age	2.72[5] Gyr
Other designations
ο Boo, 35 Boötis, BD+17°2780, GC 19858, GJ 9493, HD 129972, HIP 72125, HR 5502, SAO 101184[8]
Database references
SIMBAD	data

At the age of 2.72 billion years,^[5] this is an evolved G-type giant star with a stellar classification of G8.5 III.^[4] It belongs to the so-called red clump, which indicates it is generating energy through helium fusion at its core.^[3] Although it displays a higher abundance of barium than is normal for a star of its type, Williams (1975) considers its status as a barium star to be "very doubtful".^[9] The star has double^[5] the mass of the Sun and has expanded to 11^[7] times the Sun's radius. It is radiating 85 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,864 K.^[5]