Theta Virginis

Theta Virginis (θ Vir, θ Virginis) is a multiple star system in the zodiac constellation of Virgo. Based upon parallax measurements, it is about 320 light years from the Sun. The four[3] stars in this system have a combined apparent visual magnitude of 4.37,[2] bright enough to be seen with the naked eye.

θ Virginis
Location of θ Virginis (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Virgo
Right ascension  13h 09m 56.99067s[1]
Declination −05° 32′ 20.4185″[1]
Apparent magnitude (V) 4.37[2] (4.49 + 6.83 + 9.4 + 10.4)[3]
Characteristics
Spectral type A1Vs[4] + ? + A9m + ?[3]
U−B color index +0.00[2]
B−V color index −0.02[2]
Astrometry
Radial velocity (Rv)−2.9[5] km/s
Proper motion (μ) RA: −36.28[1] mas/yr
Dec.: −31.22[1] mas/yr
Parallax (π)10.33 ± 1.09[1] mas
Distanceapprox. 320 ly
(approx. 100 pc)
Absolute magnitude (MV)−0.52[6]
Details
θ Vir Aa
Mass3.11±0.11[7] M☉
Luminosity190[7] L☉
Surface gravity (log g)3.4[4] cgs
Temperature9,250[4] K
Rotational velocity (v sin i)4±1[4] km/s
Other designations
51 Virginis, θ Vir, BD−04°3430, FK5 490, HD 114330, HIP 64238, HR 4963, SAO 139189.[8]
Database references
SIMBADdata

The primary component, Theta Virginis Aa, is a white-hued A-type main sequence star with a stellar classification of A1Vs.[4] It is part of a spectroscopic binary[9] whose components, Aa and Ab, have visual magnitudes of +4.49 and +6.83 respectively. The system has an orbital period of about 33.04 years with an eccentricity of 0.9.[3] The brighter member of this pair shows photometric and radial velocity periodicities with a cycle time of 0.7 days, which may indicate its rotation period.[10]

The inner pair is orbited by the 9.4 magnitude B component, at an angular separation of 7.1 arcseconds. A fourth component C, 69.6 arcseconds away, has an apparent magnitude of 10.4.[3]

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. Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data, SIMBAD, Bibcode:1986EgUBV........0M.
  3. Eggleton, P. P.; Tokovinin, A. A. (September 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.
  4. Landstreet, J. D.; et al. (September 2009), "Atmospheric velocity fields in tepid main sequence stars", Astronomy and Astrophysics, 503 (3): 973–984, arXiv:0906.3824, Bibcode:2009A&A...503..973L, doi:10.1051/0004-6361/200912083.
  5. Wilson, R. E. (1953), General Catalogue of Stellar Radial Velocities, Carnegie Institute of Washington, D.C., Bibcode:1953GCRV..C......0W.
  6. Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015.
  7. Zorec, J.; Royer, F. (January 2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics, 537: A120, arXiv:1201.2052, Bibcode:2012A&A...537A.120Z, doi:10.1051/0004-6361/201117691.
  8. "tet Vir". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2016-09-05.
  9. Adelman, Saul J. (November 1997), "On the possible variability of the main sequence A stars theta Virginis and 109 Virginis", Astronomy & Astrophysics Supplement Series, 125: 497–499, Bibcode:1997A&AS..125..497A, doi:10.1051/aas:1997105.
  10. Scholz, G.; et al. (September 1998), "Spectroscopic and photometric investigations of MAIA candidate stars", Astronomy and Astrophysics, 337: 447–459, Bibcode:1998A&A...337..447S.
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