Pi Virginis

Pi Virginis (π Vir, π Virginis) is a binary star in the zodiac constellation of Virgo. It is visible to the naked eye with an apparent visual magnitude of 4.64.[2] The distance to this star, based upon parallax measurements,[1] is roughly 380 light years.

π Virginis
Location of π Virginis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Virgo
Right ascension  12h 00m 52.39042s[1]
Declination +06° 36′ 51.5571″[1]
Apparent magnitude (V) 4.64[2]
Characteristics
Spectral type A5 V[3]
U−B color index +0.12[2]
B−V color index +0.12[2]
Astrometry
Radial velocity (Rv)−10.4[4] km/s
Proper motion (μ) RA: +0.26[1] mas/yr
Dec.: −30.10[1] mas/yr
Parallax (π)8.49 ± 0.39[1] mas
Distance380 ± 20 ly
(118 ± 5 pc)
Absolute magnitude (MV)−0.70[5]
Orbit[6]
Primaryπ Virginis A
Companionπ Virginis B
Period (P)282.69 days
Semi-major axis (a)3.55 mas
Eccentricity (e)0.265
Inclination (i)62.71°
Longitude of the node (Ω)149.34°
Periastron epoch (T)2448281.3906
Argument of periastron (ω)
(secondary)		312°
Semi-amplitude (K1)
(primary)		26.20[7] km/s
Details
π Vir A
Mass2.2[7] M☉
Radius1.5[8] R☉
Surface gravity (log g)3.51[9] cgs
Temperature8,000[9] K
Rotational velocity (v sin i)71[3] km/s
Other designations
BD+07°2502, FK5 1311, HD 104321, HIP 58590, HR 4589, SAO 119164[10]
Database references
SIMBADdata

This is a spectroscopic binary system with a stellar classification of A5V. They have an orbital period of 283 days with an eccentricity of 0.27.[7] The mass ratio of the two stars is about 0.47, with the primary having an estimated mass of around 2.2 times that of the Sun. The primary is a cool metallic-lined Am star.[9]

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. Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data, Bibcode:1986EgUBV........0M.
  3. 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.
  4. Evans, D. S. (June 20–24, 1966), Batten, Alan Henry; Heard, John Frederick (eds.), "The Revision of the General Catalogue of Radial Velocities", Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30, University of Toronto: International Astronomical Union, 30, p. 57, Bibcode:1967IAUS...30...57E.
  5. 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.
  6. ESA (1997). "The Hipparcos and Tycho Catalogues". VizieR On-line Data Catalog. Bibcode:1997yCat.1239....0E.
  7. Ducati, J. R.; et al. (January 2011), "The mass ratio and initial mass functions in spectroscopic binaries" (PDF), Astronomy and Astrophysics, 525: 9, Bibcode:2011A&A...525A..26D, doi:10.1051/0004-6361/200913895, A26.
  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. Paunzen, E.; et al. (February 2013), "A photometric study of chemically peculiar stars with the STEREO satellites - II. Non-magnetic chemically peculiar stars", Monthly Notices of the Royal Astronomical Society, 429 (1): 119–125, arXiv:1211.1535, Bibcode:2013MNRAS.429..119P, doi:10.1093/mnras/sts318.
  10. "pi. Vir -- Spectroscopic binary", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2016-09-16.
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