40 Leonis

40 Leonis is a star in the zodiac constellation of Leo. It is faintly visible to the naked eye, having an apparent visual magnitude of 4.80.^[2] An annual parallax shift of 46.80 mas, as seen from Earth's orbit, yields a distance estimate of 69.7 light years. It is moving away from the Sun with a radial velocity of 5.9^[4] km/s and has a relatively high proper motion, traversing the sky at the rate of 0.315^[8] arcseconds per year.

40 Leonis

Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Leo
Right ascension	10h 19m 44.16688s[1]
Declination	+19° 28′ 15.2943″[1]
Apparent magnitude (V)	4.80[2]
Characteristics
Spectral type	F6 IV-V[3][2]
U−B color index	+0.01[2]
B−V color index	+0.45[2]
Astrometry
Radial velocity (Rv)	5.9±0.1[4] km/s
Proper motion (μ)	RA: −231.73[1] mas/yr Dec.: −214.33[1] mas/yr
Parallax (π)	46.80 ± 0.24 mas[1]
Distance	69.7 ± 0.4 ly (21.4 ± 0.1 pc)
Absolute magnitude (MV)	3.13[5]
Details[6]
Mass	1.35±0.06 M☉
Radius	1.68±0.07 R☉
Luminosity	4.4±0.9 L☉
Surface gravity (log g)	4.11±0.02 cgs
Temperature	6,450±140 K
Metallicity [Fe/H]	0.09±0.03 dex
Rotational velocity (v sin i)	17±2 km/s
Age	2.63±0.21 Gyr
Other designations
40 Leo, BD+20° 2466, HD 89449, HIP 50564, HR 4054, SAO 99065[7]
Database references
SIMBAD	data

This is an F-type star with a stellar classification of F6 IV-V,^[2] which indicates the spectrum shows traits of both a main sequence star and a more evolved subgiant star. It is a suspected Delta Scuti variable^[9] and shows a depleted lithium abundance.^[10] The star is about 2.6 billion years old with a relatively high rate of spin for its age, showing a projected rotational velocity of about 17 km/s. It has 1.35 times the mass of the Sun and 1.68 times the Sun's radius. 40 Leonis is radiating around 4.4 times the Sun's luminosity from its photosphere at an effective temperature of roughly 6,450 K.^[6]

An X-ray emission with a luminosity of (1.09±0.38)×10²⁹ erg s⁻¹ has been detected from this position, which may be coming from an undetected short-period, low mass companion.^[10] 40 Leonis has a common proper motion companion, NLTT 23781, with a wide angular separation of 5,230″ (1.453°), corresponding to a physical separation of at least 110,000 AU (1.7 ly). This magnitude 16.48 star has a class of M5 and is overluminous for its type, which may mean it is a binary system.^[10]

See also

• List of stars in Leo

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. Huang, Y.; et al. (2015), "Empirical metallicity-dependent calibrations of effective temperature against colours for dwarfs and giants based on interferometric data", Monthly Notices of the Royal Astronomical Society, 454 (3): 2863, arXiv:1508.06080, Bibcode:2015MNRAS.454.2863H, doi:10.1093/mnras/stv1991.
3. Gray, R. O.; et al. (2003), "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 Parsecs: The Northern Sample. I", The Astronomical Journal, 126 (4): 2048, arXiv:astro-ph/0308182, Bibcode:2003AJ....126.2048G, doi:10.1086/378365, S2CID 119417105.
4. Gontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system", Astronomy Letters, 32 (11): 759–771, arXiv:1606.08053, Bibcode:2006AstL...32..759G, doi:10.1134/S1063773706110065, S2CID 119231169.
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, S2CID 119257644.
6. Maestro, V.; et al. (2013), "Optical interferometry of early-type stars with PAVO@CHARA - I. Fundamental stellar properties", Monthly Notices of the Royal Astronomical Society, 434 (2): 1321, arXiv:1306.5937, Bibcode:2013MNRAS.434.1321M, doi:10.1093/mnras/stt1092.
7. "40 Leo". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-02-19.
8. 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, S2CID 2603568.
9. Hauck, B. (March 1971), "Short period variable stars. V. Delta Scuti-type stars in the Geneva system", Astronomy and Astrophysics, 11: 79, Bibcode:1971A&A....11...79H.
10. Makarov, V. V.; et al. (November 2008), "Common Proper Motion Companions to Nearby Stars: Ages and Evolution", The Astrophysical Journal, 687 (1): 566–578, arXiv:0808.3414, Bibcode:2008ApJ...687..566M, doi:10.1086/591638, S2CID 17811620, 566−578.