Omega Virginis
Star in the constellation Virgo
From Wikipedia, the free encyclopedia
Omega Virginis (ω Vir, ω Virginis) is a solitary[5] star in the zodiac constellation Virgo. It has an apparent visual magnitude of +5.2,[5] which is bright enough to be faintly visible to the naked eye. Based upon an annual stellar parallax shift of 6.56 milliarcseconds,[1] it is located about 500 light years from the Sun.
  | |
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Virgo |
| Right ascension | 11h 38m 27.60727s[1] |
| Declination | +08° 08′ 03.4663″[1] |
| Apparent magnitude (V) | 5.23 - 5.50[2][3] |
| Characteristics | |
| Evolutionary stage | AGB[4] |
| Spectral type | M4 III[5] |
| U−B color index | +1.63[6] |
| B−V color index | +1.60[6] |
| Variable type | LB[2] or SR[3] |
| Astrometry | |
| Radial velocity (Rv) | +5.13±0.52[7] km/s |
| Proper motion (μ) | RA: −3.89[1] mas/yr Dec.: +5.30[1] mas/yr |
| Parallax (π) | 6.56±0.36 mas[1] |
| Distance | 500 ± 30 ly (152 ± 8 pc) |
| Absolute magnitude (MV) | +0.2[8] |
| Details | |
| Mass | 1.55[9] M☉ |
| Radius | 138 ± 17[10][a] R☉ |
| Luminosity | 2,300±500[10] L☉ |
| Surface gravity (log g) | 0.8[8] cgs |
| Temperature | 3,400±100[10] K |
| Metallicity [Fe/H] | −0.08[8] dex |
| Other designations | |
| ω Vir, 1 Virginis, BD+08°2532, FK5 2932, HD 101153, HIP 56779, HR 4483, SAO 118965[11] | |
| Database references | |
| SIMBAD | data |
This is a red giant star with a stellar classification of M4 III.[5] It is thought to be on the asymptotic giant branch (AGB), with shells of hydrogen and helium around a carbon-oxygen core.[4] After evolving away from the main sequence it has expanded to around 140 times the solar radius,[a] and now shines with 2,300 times the luminosity of the Sun. The effective temperature of the photosphere is 3,400 K.[10]
Omega Virginis is a semiregular variable with a brightness that varies over an amplitude of 0.28 with periods of 30 and 275 days.[13] The General Catalogue of Variable Stars gives the magnitude range as 5.23 to 5.50.[2] It was formally declared a variable star in 1972 following a 1969 study showing small-amplitude variations.[14][15]
Notes
- Calculated, using the Stefan-Boltzmann law and the star's effective temperature and luminosity, with respect to the solar nominal effective temperature of 5,772 K:
