31 Boötis

31 Boötis is a single[8] star in the northern constellation of Boötes,[7] located 470 light years from the Sun.[1] It is visible to the naked eye as a faint, yellow-hued star with an apparent visual magnitude of 4.86.[2] The object is moving closer to the Earth with a heliocentric radial velocity of −16.5 km/s.[2] It was known to be part of a constellation between Virgo and Boötes named Mons Maenalus, it was also the brightest star in the constellation.

31 Boötis
Observation data
Epoch J2000      Equinox J2000
Constellation Boötes
Right ascension  14h 41m 38.75049s[1]
Declination +08° 09′ 42.3409″[1]
Apparent magnitude (V) 4.86[2]
Characteristics
Spectral type G7 IIIa[3]
B−V color index 0.992±0.038[2]
Astrometry
Radial velocity (Rv)−16.5±1.8[2] km/s
Proper motion (μ) RA: –9.589[1] mas/yr
Dec.: +3.906[1] mas/yr
Parallax (π)6.8757 ± 0.2796[1] mas
Distance470 ± 20 ly
(145 ± 6 pc)
Absolute magnitude (MV)−1.22[2]
Details
Mass3.27[4] M☉
Radius23.25+0.40
−0.49[1] R☉
Luminosity274.9±12.6[1] L☉
Surface gravity (log g)2.60[5] cgs
Temperature4,874+53
−41[1] K
Metallicity [Fe/H]−0.10[5] dex
Rotational velocity (v sin i)6.5[6] km/s
Age370[4] Myr
Other designations
31 Boo, NSV 6769, BD+08°2903, FK5 3163, GC 19789, HD 129312, HIP 71832, HR 5480, SAO 120601[7]
Database references
SIMBADdata

This is an evolved giant star with a stellar classification of G7 IIIa.[3] It is a suspected variable star of unknown type,[9] and is an X-ray source.[10] The star is 370[4] million years old with 3.27[4] times the mass of the Sun. Having exhausted the hydrogen at its core, the star has expanded to 23[1] times the Sun's radius. It is radiating 275[1] times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,874 K.[1]

References
  1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  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.
  3. Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins Catalog of Revised MK Types for the Cooler Stars", The Astrophysical Journal Supplement Series, 71: 245, Bibcode:1989ApJS...71..245K, doi:10.1086/191373.
  4. Luck, R. Earle (2015), "Abundances in the Local Region. I. G and K Giants", Astronomical Journal, 150 (3), 88, arXiv:1507.01466, Bibcode:2015AJ....150...88L, doi:10.1088/0004-6256/150/3/88.
  5. Hekker, S.; Meléndez, J. (2007), "Precise radial velocities of giant stars. III. Spectroscopic stellar parameters", Astronomy and Astrophysics, 475 (3): 1003, arXiv:0709.1145, Bibcode:2007A&A...475.1003H, doi:10.1051/0004-6361:20078233.
  6. De Medeiros, J. R.; et al. (November 2000), "Rotation and lithium in single giant stars", Astronomy and Astrophysics, 363: 239–243, arXiv:astro-ph/0010273, Bibcode:2000A&A...363..239D.
  7. "31 Boo". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved May 10, 2019.
  8. 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.
  9. Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S.
  10. Haakonsen, Christian Bernt; Rutledge, Robert E. (September 2009), "XID II: Statistical Cross-Association of ROSAT Bright Source Catalog X-ray Sources with 2MASS Point Source Catalog Near-Infrared Sources", The Astrophysical Journal Supplement, 184 (1): 138–151, arXiv:0910.3229, Bibcode:2009ApJS..184..138H, doi:10.1088/0067-0049/184/1/138.
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