31 Leonis
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Leo
Right ascension 10h 07m 54.27057s[1]
Declination +09° 59′ 51.0230″[1]
Apparent magnitude (V) 4.39[2]
Characteristics
Spectral type K3.5 IIIb Fe-1:[3]
B−V color index 1.447[4]
Astrometry
Radial velocity (Rv)+39.84±0.20[5] km/s
Proper motion (μ) RA: −128.69[1] mas/yr
Dec.: −113.60[1] mas/yr
Parallax (π)20.44 ± 1.68 mas[1]
Distance160 ± 10 ly
(49 ± 4 pc)
Absolute magnitude (MV)−0.39[2]
Details
Radius30.40±1.88[6] R☉
Luminosity (bolometric)227±31[6] L☉
Surface gravity (log g)1.81[6] cgs
Temperature4,074±8[4] K
Metallicity [Fe/H]−0.02[6] dex
Rotational velocity (v sin i)5.1[4] km/s
Other designations
31 Leo, BD+10° 2112, HD 87837, HIP 49637, HR 3980, SAO 98964[7]
Database references
SIMBADdata

31 Leonis is a binary star[8] system in the equatorial constellation of Leo. The system is visible to the naked eye in unresolved form, having a combined apparent visual magnitude of 4.39.[2] An estimated distance of around 160 light years is obtained from the annual parallax shift of 20.44 mas as seen from Earth's orbit.[1] It is moving away from the Sun with a radial velocity of +39.8 km/s.[5]

The primary member of 31 Leonis, component A, is an evolved K-type red giant[9] with a stellar classification of K3.5 IIIb Fe-1:,[3] where the suffix notation indicates an underabundance of iron in the spectrum. It has expanded to 30[6] times the Solar radius and is radiating around 227[6] times the Sun's luminosity from its photosphere at an effective temperature of 4,074 K.[4] The magnitude 13.6 secondary, component B, lies at an angular separation of 7.9 arcseconds, as of 2008.[8]

References

  1. ^ a b c d e f 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. ^ a b c 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. ^ a b Keenan, Philip C; McNeil, Raymond C (1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series, 71: 245, Bibcode:1989ApJS...71..245K, doi:10.1086/191373, S2CID 123149047.
  4. ^ a b c d Massarotti, Alessandro; et al. (January 2008), "Rotational and Radial Velocities for a Sample of 761 Hipparcos Giants and the Role of Binarity", The Astronomical Journal, 135 (1): 209–231, Bibcode:2008AJ....135..209M, doi:10.1088/0004-6256/135/1/209, S2CID 121883397.
  5. ^ a b de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, S2CID 59451347, A61.
  6. ^ a b c d e f Piau, L.; et al. (February 2011), "Surface convection and red-giant radius measurements", Astronomy and Astrophysics, 526: A100, arXiv:1010.3649, Bibcode:2011A&A...526A.100P, doi:10.1051/0004-6361/201014442, S2CID 118533297.
  7. ^ "31 Leo". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-02-18.
  8. ^ a b 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, S2CID 14878976.
  9. ^ Wood, Brian E.; et al. (October 2016), "Hubble Space Telescope Constraints on the Winds and Astrospheres of Red Giant Stars", The Astrophysical Journal, 829 (2): 13, arXiv:1607.07732, Bibcode:2016ApJ...829...74W, doi:10.3847/0004-637X/829/2/74, S2CID 119258785, 74.
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