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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.
![Thumb image](http://upload.wikimedia.org/wikipedia/commons/thumb/7/7a/OmegaVirLightCurve.png/640px-OmegaVirLightCurve.png)
Observation data Epoch J2000 Equinox J2000 | |
---|---|
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 | 70[10] R☉ |
Luminosity | 1,515[11] L☉ |
Surface gravity (log g) | 0.8[8] cgs |
Temperature | 3,490[11] K |
Metallicity [Fe/H] | −0.08[8] dex |
Other designations | |
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 70 times the solar radius,[10] and now shines with 1,515 times the luminosity of the Sun.[11] The effective temperature of the outer atmosphere is 3,490 K.[11]
Omega Virginis is a semiregular variable with a brightness that varies over an amplitude of 0.28 with periods of 30 and 275 days.[14] 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.[15][16]