Chi Virginis

Chi Virginis (χ Vir, χ Virginis) is a double star in the constellation Virgo. Based upon parallax measurements, it is approximately 294 light-years (90 parsecs) from Earth.[1] It has an apparent visual magnitude of 4.65,[2] which is bright enough to be seen with the unaided eye under suitable viewing conditions.

χ Virginis
Location of χ Virginis (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Virgo
Right ascension  12h 39m 14.76703s[1]
Declination –07° 59′ 44.0324″[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)–19.7[4] km/s
Proper motion (μ) RA: –77.13[1] mas/yr
Dec.: –24.73[1] mas/yr
Parallax (π)11.11 ± 0.29[1] mas
Distance294 ± 8 ly
(90 ± 2 pc)
Absolute magnitude (MV)−0.29 ± 0.19[5]
Details
Mass2.17 ± 0.28[6] M☉
Radius23[7] R☉
Luminosity182[7] L☉
Surface gravity (log g)2.5[7] cgs
Temperature4,395[7] K
Metallicity0.06[7]
Rotational velocity (v sin i)3.9[7] km/s
Age0.86 ± 0.34[5] Gyr
Other designations
26 Virginis, BD–07°3452, GC 17227, GCRV 7604, HD 110014, HIP 61740, HR 4813, PPM 195694, SAO 138892.[8]
Database references
SIMBADdata
Exoplanet Archivedata
Extrasolar Planets
Encyclopaedia		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[6] and has expanded to 23 times the Sun's radius, giving it a luminosity of 182 times the luminosity of the Sun.[7] The effective temperature of the star's outer envelope is about 4,395 K,[7] which gives the star the orange hue typical of K-type stars.[9] The abundance of elements other than hydrogen and helium, what astronomers term the star's metallicity, is slightly higher than in the Sun.[7]

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.[10]

In 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.[11] But on 19 August 2015, the existence of a second planet, HD 110014 c, (about three times bigger than Jupiter and having an orbit roughly that of Venus) was confirmed by Chilean astronomer Maritza Soto.[12]

The Chi Virginis planetary system
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b ≥11.09 ± 1 MJ 2.14 ± 0.03 835.477 ± 6 0.462 ± 0.069 — —

See also

References
  1. van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.
  2. Gutierrez-Moreno, A.; et al. (1966), A System of photometric standards, 1, Publicaciones Universidad de Chile, Department de Astronomy, pp. 1–17, Bibcode:1966PDAUC...1....1G
  3. Buscombe, W. (1962), "Spectral classification of Southern fundamental stars", Mount Stromlo Observatory Mimeogram, 4, Bibcode:1962MtSOM...4....1B
  4. Wilson, R. E. (1953), General Catalogue of Stellar Radial Velocities, Carnegie Institute of Washington D.C., Bibcode:1953GCRV..C......0W
  5. 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
  6. Kunitomo, M.; et al. (2011), "Planet Engulfment by ~1.5–3 M⊙ Red Giants", The Astrophysical Journal, 737 (2): 66, arXiv:1106.2251, Bibcode:2011ApJ...737...66K, doi:10.1088/0004-637X/737/2/66
  7. 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
  8. "chi Vir -- Star in double system", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2011-12-30
  9. "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on 2012-03-10, retrieved 2012-01-16
  10. 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
  11. 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
  12. http://m.gadgets.ndtv.com/science/news/astronomer-discovers-planet-3-times-as-large-as-jupiter-730075
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