Nu Leonis

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]

ν Leonis

Location of ν Leonis (circled)
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Leo
Right ascension	09h 58m 13.37557s[1]
Declination	+12° 26′ 41.2865″[1]
Apparent magnitude (V)	5.15[2]
Characteristics
Spectral type	B6 IV[3]
U−B color index	−0.13[2]
B−V color index	−0.04[2]
Astrometry
Radial velocity (Rv)	+14.4[4] km/s
Proper motion (μ)	RA: −25.66[1] mas/yr Dec.: −15.56[1] mas/yr
Parallax (π)	6.53±0.24 mas[1]
Distance	500 ± 20 ly (153 ± 6 pc)
Absolute magnitude (MV)	−0.66[5]
Orbit[6]
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[7] M☉
Radius	2.3[8] R☉
Luminosity	244[7] L☉
Temperature	9,552[9] K
Rotational velocity (v sin i)	100[7] km/s
Other designations
ν Leo, 27 Leo, BD+13°2183, HD 86360, HIP 48883, HR 3937, SAO 98876[10]
Database references
SIMBAD	data

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]