Chi Virginis (χ Vir, χ Virginis) is a double star in the constellation Virgo. Based upon parallax measurements, it is approximately 315 light-years (97 parsecs) from Earth. It has an apparent visual magnitude of 4.65, which is bright enough to be seen with the unaided eye under suitable viewing conditions.
  | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Virgo |
| Right ascension | 12h 39m 14.76696s[1] |
| Declination | −07° 59′ 44.0338″[1] |
| Apparent magnitude (V) | 4.652[2] |
| Characteristics | |
| Spectral type | K2 III[3] |
| U−B color index | +1.389[2] |
| B−V color index | +1.239[2] |
| Astrometry | |
| Radial velocity (Rv) | −18.11±0.07[4] km/s |
| Proper motion (μ) | RA: −77.223[1] mas/yr Dec.: −24.409[1] mas/yr |
| Parallax (π) | 10.3526 ± 0.1151 mas[1] |
| Distance | 315 ± 4 ly (97 ± 1 pc) |
| Absolute magnitude (MV) | −0.29±0.19[5] |
| Details[4] | |
| Mass | 2.28±0.35 M☉ |
| Radius | 20.15±2 R☉ |
| Luminosity | 107 L☉ |
| Surface gravity (log g) | 2.15±0.1 cgs |
| Temperature | 4,559±53 K |
| Metallicity | 0.05±0.1 |
| Rotational velocity (v sin i) | 2.52±0.45 km/s |
| Age | 0.86±0.34[5] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
This star has a stellar classification of K2 III,[3] with the luminosity class "III" indicating that this is a giant star that has consumed the hydrogen at its core and evolved away from the main sequence. It has a mass about double that of the Sun and has expanded to 20 times the Sun's radius, giving it a luminosity of 107 times the luminosity of the Sun. The effective temperature of the star's outer envelope is about 4,559 K,[4] which gives the star the orange hue typical of K-type stars.[7] The abundance of elements other than hydrogen and helium, what astronomers term the star's metallicity, is slightly higher than in the Sun.[8][4]
This star has three optical companions. At an angular separation of 173.1 arcseconds is a magnitude +9.1 star, which is of spectral type K0. A 10th magnitude star is located 221.2 arcseconds away, and the third is a magnitude +9.1 K2 star 321.2 arcseconds away. None of these have been confirmed as a physical companion.[9]
Planetary system
editIn July 2009, it was discovered that Chi Virginis has a massive planet with a high orbital eccentricity of 0.46. It is orbiting with a period of about 835 days and has a mass at least 11 times greater than Jupiter. There are indications of a second planet orbiting with a period of 130 days, but this has not been firmly established.[10]
In May 2015, the existence of a second planet candidate, HD 110014 c, (Chi Virginis c, about three times the mass of Jupiter and having an orbit roughly that of Venus) was announced by Chilean astronomer Maritza Soto. The two-planet model could not be confirmed, and the radial velocity variations attributed to the second planet might instead be caused by a starspot.[11] A 2021 review of planets around giant stars lists this second planet as "questionable".[12]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| c (unconfirmed) | ≥3.1±0.4 MJ | 0.64±0.003 | 130.0±0.9 | 0.44±0.2 | — | — |
| b | ≥10.7±1.0 MJ | 2.31±0.04 | 882.6±21.5 | 0.26±0.1 | — | — |
See also
editReferences
edit- ^ a b c d e Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- ^ a b c Gutierrez-Moreno, A.; et al. (1966), "A System of photometric standards", Publications of the Department of Astronomy University of Chile, 1, Publicaciones Universidad de Chile, Department de Astronomy: 1–17, Bibcode:1966PDAUC...1....1G
- ^ a b Buscombe, W. (1962), "Spectral classification of Southern fundamental stars", Mount Stromlo Observatory Mimeogram, 4: 1, Bibcode:1962MtSOM...4....1B
- ^ a b c d Jofré, E.; Petrucci, R.; Saffe, C.; Saker, L.; Artur de la Villarmois, E.; Chavero, C.; Gómez, M.; Mauas, P. J. D. (2015-02-01). "Stellar parameters and chemical abundances of 223 evolved stars with and without planets". Astronomy and Astrophysics. 574: A50. arXiv:1410.6422. Bibcode:2015A&A...574A..50J. doi:10.1051/0004-6361/201424474. ISSN 0004-6361. Chi Virginis' database entry at VizieR.
- ^ a b da Silva, L.; et al. (2006), "Basic physical parameters of a selected sample of evolved stars", Astronomy and Astrophysics, 458 (2): 609–623, arXiv:astro-ph/0608160, Bibcode:2006A&A...458..609D, doi:10.1051/0004-6361:20065105, S2CID 9341088
- ^ "chi Vir -- Star in double system", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2011-12-30
- ^ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on 2012-03-18, retrieved 2012-01-16
- ^ Massarotti, A.; Latham, D. W.; Stefanik, R. P.; Fogel, J. (2008), "Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity", The Astronomical Journal, 135 (1): 209–231, Bibcode:2008AJ....135..209M, doi:10.1088/0004-6256/135/1/209, S2CID 121883397
- ^ Eggleton, P. P.; Tokovinin, A. A. (2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976
- ^ de Medeiros, J. R.; et al. (2009), "A planet around the evolved intermediate-mass star HD 110014", Astronomy and Astrophysics, 504 (2): 617–623, Bibcode:2009A&A...504..617D, doi:10.1051/0004-6361/200911658
- ^ a b Soto, M. G.; et al. (August 2015). "RAFT - I. Discovery of new planetary candidates and updated orbits from archival FEROS spectra". Monthly Notices of the Royal Astronomical Society. 451 (3): 3131–3144. arXiv:1505.04796. Bibcode:2015MNRAS.451.3131S. doi:10.1093/mnras/stv1144. S2CID 49332927.
- ^ Döllinger, M. P.; Hartmann, M. (September 2021). "A Sanity Check for Planets around Evolved Stars". The Astrophysical Journal Supplement Series. 256 (1): 10. Bibcode:2021ApJS..256...10D. doi:10.3847/1538-4365/ac081a. S2CID 237369556.