Astronomy:Omicron Virginis
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| Observation data Equinox J2000.0]] (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[6] mas/yr Dec.: +33.282[6] mas/yr |
| Parallax (π) | 19.4936 ± 0.1658[6] mas |
| Distance | 167 ± 1 ly (51.3 ± 0.4 pc) |
| Absolute magnitude (MV) | +0.52[7] |
| Orbit[8] | |
| Primary | A |
| Companion | 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 | |
| Database references | |
| SIMBAD | data |
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.
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]
References
- ↑ 1.0 1.1 van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653–664. doi:10.1051/0004-6361:20078357. Bibcode: 2007A&A...474..653V.
- ↑ Mallik, Sushma V. (December 1999). "Lithium abundance and mass". Astronomy and Astrophysics 352: 495–507. Bibcode: 1999A&A...352..495M.
- ↑ Laney, C. D.; Joner, M. D.; Pietrzyński, G. (2012). "A new Large Magellanic Cloud K-band distance from precision measurements of nearby red clump stars". Monthly Notices of the Royal Astronomical Society 419 (2): 1637. doi:10.1111/j.1365-2966.2011.19826.x. Bibcode: 2012MNRAS.419.1637L.
- ↑ 4.0 4.1 Keenan, Philip C.; McNeil, Raymond C. (1989). "The Perkins catalog of revised MK types for the cooler stars". Astrophysical Journal Supplement Series 71: 245. doi:10.1086/191373. Bibcode: 1989ApJS...71..245K.
- ↑ 5.0 5.1 5.2 Jofré, E.; Petrucci, R.; Saffe, C.; Saker, L.; de la Villarmois, E. Artur; Chavero, C.; Gómez, M.; Mauas, P. J. D. (2015). "Stellar parameters and chemical abundances of 223 evolved stars with and without planets". Astronomy & Astrophysics 574: A50. doi:10.1051/0004-6361/201424474. Bibcode: 2015A&A...574A..50J.
- ↑ 6.0 6.1 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 Gaia DR3 record for this source at VizieR.
- ↑ 7.0 7.1 Takeda, Yoichi et al. (August 2008). "Stellar Parameters and Elemental Abundances of Late-G Giants". Publications of the Astronomical Society of Japan 60 (4): 781–802. doi:10.1093/pasj/60.4.781. Bibcode: 2008PASJ...60..781T.
- ↑ 8.0 8.1 8.2 8.3 8.4 Escorza, A.; De Rosa, R. J. (March 2023). "Barium and related stars, and their white-dwarf companions: III. The masses of the white dwarfs". Astronomy & Astrophysics 671: A97. doi:10.1051/0004-6361/202244782. ISSN 0004-6361. Bibcode: 2023A&A...671A..97E.
- ↑ 9.0 9.1 Baines, Ellyn K.; Clark, James H.; Kingsley, Bradley I.; Schmitt, Henrique R.; Stone, Jordan M. (2025-05-07). "Vintage NPOI: New and Updated Angular Diameters for 145 Stars" (in en). The Astronomical Journal 169 (6): 293. doi:10.3847/1538-3881/adc930. ISSN 1538-3881. Bibcode: 2025AJ....169..293B.
- ↑ Reffert, Sabine; Bergmann, Christoph; Quirrenbach, Andreas; Trifonov, Trifon; Künstler, Andreas (2015). "Precise radial velocities of giant stars. VII. Occurrence rate of giant extrasolar planets as a function of mass and metallicity". Astronomy & Astrophysics 574: A116. doi:10.1051/0004-6361/201322360. Bibcode: 2015A&A...574A.116R.
- ↑ Böhm-Vitense, Erika; Carpenter, Kenneth; Robinson, Richard; Ake, Tom; Brown, Jeffery (2000). "Do All BA II Stars Have White Dwarf Companions?". The Astrophysical Journal 533 (2): 969. doi:10.1086/308678. Bibcode: 2000ApJ...533..969B.
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