Tau Virginis

Tau Virginis (τ Vir, τ Virginis) is a single[13] star in the zodiac constellation Virgo. With an apparent visual magnitude of 4.28,[2] it is faintly visible to the naked eye. The distance to Tau Virginis, based upon parallax measurements, is approximately 225 light years with a margin of error of ±3 light years.

τ Virginis
Location of τ Virginis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Virgo
Right ascension  14h 01m 38.79341s[1]
Declination +01° 32′ 40.3145″[1]
Apparent magnitude (V) 4.2777±0.0007[2]
Characteristics
Spectral type A2IV/V[3]
U−B color index +0.12[4]
B−V color index +0.11[4]
Astrometry
Radial velocity (Rv)−6.7±0.9[5] km/s
Proper motion (μ) RA: +17.49[1] mas/yr
Dec.: −21.27[1] mas/yr
Parallax (π)14.50 ± 0.18[1] mas
Distance225 ± 3 ly
(69.0 ± 0.9 pc)
Absolute magnitude (MV)+0.5[6]
Details
Mass1.96[7] M☉
Radius1.6[8] R☉
Luminosity70[9] L☉
Surface gravity (log g)3.39[7] cgs
Temperature8,413±286[7] K
Metallicity [Fe/H]−0.19[10] dex
Rotational velocity (v sin i)186[11] km/s
Age724[7] Myr
Other designations
τ Vir, 93 Virginis, BD+02°2761, FK5 516, HD 122408, HIP 68520, HR 5264, SAO 120238[12]
Database references
SIMBADdata

This star has a stellar classification of A2IV/V,[3] which matches the spectrum of an A-type main sequence star mixed with spectral traits of a subgiant. It is about 700[7] million years old and is spinning rapidly with a projected rotational velocity of 186 km/s.[11] The star has nearly double[7] the mass of the Sun and about 160% of the Sun's radius.[8] It shines with 70[9] times the luminosity of the Sun and has an effective temperature of 8413 K in its outer atmosphere.[7]

Tau Virginis has multiple visual companions, listed below:[14]

Companion Visual
Magnitude		 Angular
Separation		 Position
Angle		 Year
Measured
B9.4182.70″287°2012
C13.10176.70″353°2000
D9.68342.70″85°2012
E12.0014.6″175°2009

References
  1. van Leeuwen, F. (November 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. Adelman, S. J. (February 2001). "Research Note Hipparcos photometry: The least variable stars". Astronomy and Astrophysics. 367 (1): 297–298. Bibcode:2001A&A...367..297A. doi:10.1051/0004-6361:20000567.
  3. Houk, N.; Swift, C. (1999), "Michigan catalogue of two-dimensional spectral types for the HD Stars, Vol. 5", Michigan Spectral Survey, 05, Bibcode:1999MSS...C05....0H
  4. Mermilliod, J.-C. (1986), Compilation of Eggen's UBV data, transformed to UBV (unpublished), SIMBAD, Bibcode:1986EgUBV........0M
  5. Gontcharov, G. A. (2006), "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system", Astronomy Letters, 32 (11): 759–771, arXiv:1606.08053, Bibcode:2006AstL...32..759G, doi:10.1134/S1063773706110065.
  6. Blondel, P. F. C.; Djie, H. R. E. Tjin A. (September 2006), "Modeling of PMS Ae/Fe stars using UV spectra" (PDF), Astronomy and Astrophysics, 456 (3): 1045–1068, Bibcode:2006A&A...456.1045B, doi:10.1051/0004-6361:20040269.
  7. David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146.
  8. Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics", Astronomy and Astrophysics, 367 (2): 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451.
  9. McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x.
  10. Morossi, C.; et al. (September 2002), "Metallicity Determinations from Ultraviolet-Visual Spectrophotometry. I. The Test Sample", The Astrophysical Journal, 577 (1): 377–388, Bibcode:2002ApJ...577..377M, doi:10.1086/342144.
  11. Royer, F.; et al. (February 2007), "Rotational velocities of A-type stars. III. Velocity distributions", Astronomy and Astrophysics, 463 (2): 671–682, arXiv:astro-ph/0610785, Bibcode:2007A&A...463..671R, doi:10.1051/0004-6361:20065224.
  12. "* tau Vir". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2016-09-16.
  13. 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.
  14. Mason, B. D.; et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal, 122: 3466–3471, Bibcode:2001AJ....122.3466M, doi:10.1086/323920, retrieved 2015-07-22.
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