Omicron Virginis
Star in the constellation Virgo
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Omicron Virginis (ο Vir, ο Virginis) is a binary star in the zodiac constellation of Virgo. It is visible to the naked eye with an apparent visual magnitude of +4.12.[7] Based upon parallax measurements, it is at a distance of 163 light years.
 | |
| Observation data Epoch J2000.0 Equinox ICRS | |
|---|---|
| Constellation | Virgo |
| Right ascension | 12h 05m 12.54049s[1] |
| Declination | +08° 43′ 58.7498″[1] |
| Apparent magnitude (V) | 4.12[2] |
| Characteristics | |
| Evolutionary stage | Red-giant branch[3] |
| Spectral type | G8 IIIa CN-1Ba1CH1[4] |
| Astrometry | |
| Radial velocity (Rv) | −29.62[5] km/s |
| Proper motion (μ) | RA: −225.029 mas/yr[6] Dec.: +33.282 mas/yr[6] |
| Parallax (π) | 19.4936±0.1658 mas[6] |
| Distance | 167 ± 1 ly (51.3 ± 0.4 pc) |
| Absolute magnitude (MV) | +0.52[7] |
| Orbit[8] | |
| Primary | A |
| Name | B |
| Period (P) | 50.70±3.30 yr |
| Semi-major axis (a) | 21.1±1.7 au |
| Eccentricity (e) | 0.12±0.04 |
| Inclination (i) | 147.8±1.6° |
| Longitude of the node (Ω) | 34±2° |
| Periastron epoch (T) | 2460663±500 |
| Argument of periastron (ω) (secondary) | 180±17° |
| Details[5] | |
| A | |
| Mass | 2.7±0.2[8] M☉ |
| Radius | 11.2±0.3[9] R☉ |
| Luminosity | 57 L☉ |
| Surface gravity (log g) | 3.17 cgs |
| Temperature | 5,107 K |
| Metallicity [Fe/H] | −0.30 dex |
| Rotational velocity (v sin i) | 2.23 km/s |
| Age | 0.88 Gyr |
| B | |
| Mass | 0.94±0.14[8] M☉ |
| Other designations | |
| 9 Virginis, ο Vir, BD+09°2583, FK5 450, GJ 3703, HD 104979, HIP 58948, HR 4608, SAO 119213 | |
| Database references | |
| SIMBAD | data |
Characteristics
The components are orbiting around the system's center of mass at a period of 50.7 years, and a nearly circular orbit with eccentricity 0.12 and an average separation of 21 astronomical units.[8]
The primary star is a G-type giant with a stellar classification of G8 IIIa CN-1Ba1CH1.[4] This indicates that it is a Barium star. It is around 11 times larger than the Sun.[9] Although it is slightly cooler, it is radiating about 57 times the luminosity of the Sun. It is over twice as massive as the Sun and is around a billion years old.[5] A simplified statistical analysis suggests that ο Virginis is likely to be a red-giant branch star fusing hydrogen in a shell around an inert helium core, but there is about a 22% chance that it is a horizontal branch star fusing helium in its core.[10]
The secondary is a white dwarf with 94% of the Sun's mass. It contamined the surface of the giant primary with s-process elements when it was on the asymptotic giant branch, causing it to be a Barium star.[8] It may also explain the unexpected SiIV emission flux coming from Omicron Virginis.[11]