25 Canum Venaticorum

25 Canum Venaticorum is a binary star[10] system in the northern constellation of Canes Venatici, approximately 199[1] light years from the Sun. It is visible to the naked eye as a faint, white-hued star with a combined apparent visual magnitude of +4.82[2] The system is moving closer to the Earth with a heliocentric radial velocity of roughly −10 km/s.[2]

25 Canum Venaticorum
Observation data
Epoch J2000      Equinox J2000
Constellation Canes Venatici
Right ascension 13h 37m 27.62782s[1]
Declination +36° 17′ 41.6337″[1]
Apparent magnitude (V) +4.82[2] (4.98 + 6.95)[3]
Characteristics
Spectral type A7 III + A8 V:[4]
Astrometry
Radial velocity (Rv)−10.4±2.1[2] km/s
Proper motion (μ) RA: −95.54[1] mas/yr
Dec.: +23.75[1] mas/yr
Parallax (π)16.42 ± 0.53[1] mas
Distance199 ± 6 ly
(61 ± 2 pc)
Absolute magnitude (MV)0.90[2]
Orbit[5]
Period (P)228 yr
Semi-major axis (a)1.02″
Eccentricity (e)0.80
Inclination (i)147°
Longitude of the node (Ω)87°
Periastron epoch (T)1864.0
Argument of periastron (ω)
(secondary)		159°
Details
25 CVn A
Mass2.23[6] M☉
Surface gravity (log g)3.85[7] cgs
Temperature7,609±259[7] K
Rotational velocity (v sin i)235[8] km/s
Age659[7] Myr
25 CVn B
Mass1.58[6] M☉
Other designations
25 CVn, BD+37° 2433, FK5 3083, GC 18421, HD 118623, HIP 66458, HR 5127, SAO 63648, ADS 8974, CCDM 13375+3617, WDS J13375+3618[9]
Database references
SIMBADdata

This is a wide binary system with an orbital period of 228 years and an eccentricity of 0.80.[5] As of 2001, they had a projected separation of 107.0 AU.[6] The magnitude 4.98[3] primary, component A, has a stellar classification of A7 III,[4] which matches an A-type giant star. It is 659[7] million years old with a projected rotational velocity of 235 km/s. This rate of spin is giving the star an oblate shape with an equatorial bulge that is an estimated 27% larger than the polar radius.[8] The companion, component B, is a magnitude 6.95[3] A-type main-sequence star with a class of A8 V:.[4] The ':' suffix indicates some uncertainty in the classification of this star.

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, S2CID 18759600.
  2. 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. S2CID 119257644.
  3. Mason, B. D.; et al. (December 2001), "The Washington Visual Double Star Catalog (WDS), Version 2019-01-21", The Astronomical Journal, U. S. Naval Observatory, Washington D.C., 122 (6): 3466–3471, Bibcode:2001AJ....122.3466M, doi:10.1086/323920.
  4. Stephenson, C. B.; Sanwal, N. B. (June 1969), "The masses of stars above the main sequence", Astronomical Journal, 74: 689–704, Bibcode:1969AJ.....74..689S, doi:10.1086/110845.
  5. Söderhjelm, Staffan (1999), "Visual binary orbits and masses POST HIPPARCOS", Astronomy and Astrophysics, 341: 121–140, Bibcode:1999A&A...341..121S.
  6. De Rosa, R. J.; Patience, J.; Wilson, P. A.; Schneider, A.; Wiktorowicz, S. J.; Vigan, A.; Marois, C.; Song, I.; Macintosh, B.; Graham, J. R.; Doyon, R.; Bessell, M. S.; Thomas, S.; Lai, O. (2014), "The VAST Survey - III. The multiplicity of A-type stars within 75 pc", Monthly Notices of the Royal Astronomical Society, 437 (2): 1216–1240, arXiv:1311.7141, Bibcode:2014MNRAS.437.1216D, doi:10.1093/mnras/stt1932.
  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, S2CID 33401607.
  8. van Belle, Gerard T. (March 2012), "Interferometric observations of rapidly rotating stars", The Astronomy and Astrophysics Review, 20 (1): 51, arXiv:1204.2572, Bibcode:2012A&ARv..20...51V, doi:10.1007/s00159-012-0051-2, S2CID 119273474.
  9. "25 CVn". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-07-27.
  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, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
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