38 Leonis Minoris

38 Leonis Minoris is a binary star[3] system in the northern constellation of Leo Minor. It shines with a combined light of apparent magnitude 5.84,[2] which indicates it a dimly visible to the naked eye under good viewing conditions. An annual parallax shift of 19.11[1] mas provides a distance estimate of around 171 light years. It has a relatively high proper motion, traversing the celestial sphere at a rate of 0.226 arcseconds per year,[10] and is moving away from the Sun with a radial velocity of +31 km/s.[4]

38 Leonis Minoris
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Leo Minor
Right ascension 10h 39m 07.63244s[1]
Declination +37° 54′ 36.0035″[1]
Apparent magnitude (V) 5.84[2]
Characteristics
Spectral type G0 IV[3]
B−V color index 0.595±0.003[2]
Astrometry
Radial velocity (Rv)+30.9±0.3[4] km/s
Proper motion (μ) RA: −220.50[1] mas/yr
Dec.: −45.31[1] mas/yr
Parallax (π)19.11 ± 0.37[1] mas
Distance171 ± 3 ly
(52 ± 1 pc)
Absolute magnitude (MV)2.26[5]
Orbit[5]
Period (P)7.7991499±0.0000037 d
Eccentricity (e)0.023±0.034
Periastron epoch (T)20,165.164±1.470 HJD
Argument of periastron (ω)
(secondary)		285.56±68.51°
Semi-amplitude (K1)
(primary)		24.10±0.73 km/s
Details
38 LMi A
Mass1.68[6] M☉
Luminosity11.32[2] L☉
Surface gravity (log g)3.73[6] cgs
Temperature6,106[7] K
Metallicity [Fe/H]+0.32[7] dex
Rotational velocity (v sin i)14.5±1.0[5] km/s
Age2.03±0.14[7] Gyr
38 LMi B
Mass≥ 0.31[8] M☉
Other designations
38 LMi, BD+38° 2166, FK5 2852, HD 92168, HIP 52139, HR 4168, SAO 62178[9]
Database references
SIMBADdata

This is a single-lined spectroscopic binary[3] with an orbital period of 7.8 days and a low eccentricity of 0.023 – nearly circular.[5] The visible component has a stellar classification of G0 IV,[3] matching a G-type subgiant star that is exhausting the hydrogen at its core and evolving into a giant. It is about two[7] billion years old with 1.68[6] times the mass of the Sun and is spinning with a projected rotational velocity of 14.5 km/s.[5] The star has a higher than solar abundance of iron in its spectrum.[7] It is radiating 11[2] times the Sun's luminosity from its photosphere at an effective temperature of 6,106 K.[7]

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.
  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. Abt, Helmut A. (2009), "MK Classifications of Spectroscopic Binaries", The Astrophysical Journal Supplement, 180 (1): 117–18, Bibcode:2009ApJS..180..117A, doi:10.1088/0067-0049/180/1/117.
  4. 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, A61.
  5. Willmarth, Daryl W.; et al. (August 2016), "Spectroscopic Orbits for 15 Late-type Stars" (PDF), The Astronomical Journal, 152 (2): 13, Bibcode:2016AJ....152...46W, doi:10.3847/0004-6256/152/2/46, 46.
  6. Casagrande, L.; et al. (June 2011), "New constraints on the chemical evolution of the solar neighbourhood and Galactic disc(s). Improved astrophysical parameters for the Geneva-Copenhagen Survey", Astronomy and Astrophysics, 530: A138, arXiv:1103.4651, Bibcode:2011A&A...530A.138C, doi:10.1051/0004-6361/201016276.
  7. Pace, G. (March 2013), "Chromospheric activity as age indicator. An L-shaped chromospheric-activity versus age diagram", Astronomy & Astrophysics, 551: 4, arXiv:1301.5651, Bibcode:2013A&A...551L...8P, doi:10.1051/0004-6361/201220364, L8.
  8. Tokovinin, A.; et al. (May 2006), "Tertiary companions to close spectroscopic binaries", Astronomy and Astrophysics, 450 (2): 681–69, arXiv:astro-ph/0601518, Bibcode:2006A&A...450..681T, doi:10.1051/0004-6361:20054427.
  9. "38 LMi". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-02-20.
  10. Lépine, Sébastien; Shara, Michael M. (March 2005), "A Catalog of Northern Stars with Annual Proper Motions Larger than 0.15" (LSPM-NORTH Catalog)", The Astronomical Journal, 129 (3): 1483–1522, arXiv:astro-ph/0412070, Bibcode:2005AJ....129.1483L, doi:10.1086/427854.
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