Nu Leonis

ν Leonis
	Location of ν Leonis (circled)
Observation data; Epoch J2000.0 Equinox J2000.0 (ICRS)
Constellation	Leo
Right ascension	09h 58m 13.37557s
Declination	+12° 26′ 41.2865″
Apparent magnitude (V)	5.15
Characteristics
Spectral type	B6 IV
U−B color index	−0.13
B−V color index	−0.04
Astrometry
Radial velocity (Rv)	+14.4 km/s
Proper motion (μ)	RA: −25.66 mas/yr ; Dec.: −15.56 mas/yr
Parallax (π)	6.53 ± 0.24 mas
Distance	500 ± 20 ly ; (153 ± 6 pc)
Absolute magnitude (MV)	−0.66
Orbit
Period (P)	137.2978 d
Eccentricity (e)	0.7
Longitude of the node (Ω)	293.7°
Periastron epoch (T)	2419815.9 JD
Semi-amplitude (K1); (primary)	20 km/s
Details
Mass	3.37±0.05 M☉
Radius	2.3 R☉
Luminosity	244 L☉
Temperature	9,552 K
Rotational velocity (v sin i)	100 km/s
Other designations
	ν Leo, 27 Leo, BD+13°2183, HD 86360, HIP 48883, HR 3937, SAO 98876
Database references
SIMBAD	data

ν Leonis, Latinised as Nu Leonis, is a binary star system in the zodiac constellation of Leo. It is faintly visible to the naked eye with an apparent visual magnitude of 5.15;^[2] parallax measurements^[1] indicate it is around 500 light years away. At this distance, the visual extinction from interstellar dust is 0.33 magnitudes.^[11]

It is 0.05 degree north of the ecliptic, so it can be occulted by the moon or planets.

This is a single-lined spectroscopic binary system with an orbital period of 137.3 days and an eccentricity of 0.7.^[6] The primary component is a B-type subgiant star with a stellar classification of B6 IV.^[3] It has about 3.37 times the mass of the Sun,^[7] 2.3 times the Sun's radius,^[8] and radiates 244^[7] times the luminosity of the Sun from an outer atmosphere with an effective temperature of 9,552 K.^[9] The rotation rate is moderate with a projected rotational velocity of 100 km/s.^[7] Little is known about the companion.^[6]

References

^ ^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.
^ ^a ^b ^c ^d Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data, SIMBAD, Bibcode:1986EgUBV........0M.
^ ^a ^b Cowley, A.; et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal, 74: 375–406, Bibcode:1969AJ.....74..375C, doi:10.1086/110819.
^ Evans, D. S. (June 20–24, 1966), "The Revision of the General Catalogue of Radial Velocities", in Batten, Alan Henry; Heard, John Frederick (eds.), Determination of Radial Velocities and their Applications, Proceedings of IAU Symposium no. 30, vol. 30, University of Toronto: International Astronomical Union, p. 57, Bibcode:1967IAUS...30...57E.
^ 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.
^ ^a ^b ^c Harmanec, P.; et al. (May 1985), "A spectroscopic orbit of the late B star 27 Leo", Bulletin Astronomical Institutes of Czechoslovakia, 36: 160–172, Bibcode:1985BAICz..36..160H.
^ ^a ^b ^c ^d ^e ^f Zorec, J.; Royer, F. (January 2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics, 537: A120, arXiv:1201.2052, Bibcode:2012A&A...537A.120Z, doi:10.1051/0004-6361/201117691, S2CID 55586789.
^ ^a ^b Pasinetti Fracassini, L. E.; et al. (2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) – Third edition – Comments and statistics", Astronomy & Astrophysics, 367 (2): 521–24, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451, S2CID 425754.
^ ^a ^b McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x, S2CID 118665352.
^ "* nu. Leo". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2016-09-29.{{cite web}}: CS1 maint: postscript (link)
^ van Belle, Gerard T.; von Braun, Kaspar (2009), "Directly Determined Linear Radii and Effective Temperatures of Exoplanet Host Stars", The Astrophysical Journal, 694 (2): 1085–1098, arXiv:0901.1206, Bibcode:2009ApJ...694.1085V, doi:10.1088/0004-637X/694/2/1085, S2CID 18370219.