Omicron Boötis
Star in the constellation Boötes
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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]
 | |
| 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]