Nu3 Canis Majoris

Nu³ Canis Majoris is a binary star^[4] system in the southern constellation of Canis Major. Its name is a Bayer designation that is Latinized from ν³ Canis Majoris, and abbreviated Nu³ CMa or ν³ CMa. The star system, appearing as one star, is deemed visible to the naked eye with its combined apparent visual magnitude of 4.41.^[3] Based upon an annual parallax shift of 6.79 mas as seen from Earth,^[2] this system is approximately 481 light-years (147 pc) distant from the Sun.

For other stars with this Bayer designation, see ν Canis Majoris.

Nu³ Canis Majoris

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Canis Major[1]
Right ascension	06h 37m 53.421s[2]
Declination	−18° 14′ 14.93″[2]
Apparent magnitude (V)	4.41[3] (4.63 + 8.56)[4]
Characteristics
Evolutionary stage	horizontal branch[5]
Spectral type	K0 II-III[6]
U−B color index	+1.04[3]
B−V color index	+1.16[3]
Astrometry
Radial velocity (Rv)	−1.50±0.70[7] km/s
Proper motion (μ)	RA: −7.166 mas/yr[2] Dec.: −8.777 mas/yr[2]
Parallax (π)	6.7876±0.1054 mas[2]
Distance	481 ± 7 ly (147 ± 2 pc)
Absolute magnitude (MV)	−1.13[1]
Details[6]
ν3 CMa A
Mass	3.38±0.37[5] M☉
Radius	32.7 R☉
Luminosity	398 L☉
Surface gravity (log g)	2.34 cgs
Temperature	4,510 K
Metallicity [Fe/H]	−0.24 dex
Rotation	183 d
Rotational velocity (v sin i)	8[8] km/s
Age	380±20[5] Myr
Other designations
HDS 915, ν3 CMa, 8 Canis Majoris, BD−18°1492, GC 8660, HD 47442, HIP 31700, HR 2443, SAO 151730, CCDM 06379-1814, WDS J06379-1814A[9]
Database references
SIMBAD	data

Characteristics

The primary member, component A, is an evolved, orange-hued giant/bright giant hybrid with an apparent magnitude of +4.63^[4] and a stellar classification of K0 II-III.^[6] It is most likely (96% chance) on the horizontal branch,^[5] which would indicate it is generated energy through helium fusion at its core. The star has a moderate level of surface activity with a magnetic field strength of 2.2±0.4 G and is a source of X-ray emission with a luminosity of 624×10²⁷ erg s⁻¹.^[6]

This giant has an estimated 3.4^[5] times the mass of the Sun and has expanded to 33^[6] times the Sun's radius. It is radiating 398 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,510 K.^[6] The star is spinning with the leisurely period of 183 days.^[6] Its companion, component B has been observed at 1.040 arcseconds distant along a position angle of 2.9° as of 2002,^[10] and has an apparent magnitude of +8.56.^[4]