Xi2 Canis Majoris

Xi² Canis Majoris is an astrometric binary^[4] star system in the southern constellation of Canis Major. Its name is Latinized from ξ² Canis Majoris, and abbreviated Xi² CMa or ξ² CMa. With an apparent visual magnitude of +4.54,^[2] it is bright enough to be visible to the naked eye. Based upon an annual parallax shift of 8.03 mas,^[1] the system is approximately 410 light years distant from Earth. It is receding with a radial velocity of +22 km/s.^[1]

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

Xi² Canis Majoris

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Canis Major
Right ascension	06h 35m 03.388s[1]
Declination	−22° 57′ 53.26″[1]
Apparent magnitude (V)	+4.54[2]
Characteristics
Spectral type	A0 V[3][4] or A0 III[5]
U−B color index	−0.01[2]
B−V color index	−0.06[2]
Astrometry
Radial velocity (Rv)	+22.11±0.60[1] km/s
Proper motion (μ)	RA: +16.316 mas/yr[1] Dec.: +16.885 mas/yr[1]
Parallax (π)	8.0342±0.2216 mas[1]
Distance	410 ± 10 ly (124 ± 3 pc)
Absolute magnitude (MV)	+0.94[6]
Details
Mass	4.08±0.20[7] M☉
Radius	5.959[8] R☉
Luminosity	247[8] L☉
Temperature	9,381[8] K
Rotational velocity (v sin i)	145[9] km/s
Age	339[6] Myr
Other designations
ξ2 CMa, 5 Canis Majoris, BD−22°1458, FK5 249, GC 8577, HD 46933, HIP 31416, HR 2414, SAO 171982[10]
Database references
SIMBAD	data

The binary nature of this system was determined based on changes in the proper motion of the visible component.^[11] W. Buscombe (1962) gave the white-hued primary a stellar classification of A0 V,^[3] indicating it is an A-type main-sequence star. However, N. Houk and M. Smith-Moore (1978) list it with a class of A0 III,^[5] which would match a more evolved giant star, also of the A-type. It is 339^[6] million years old with a high rate of spin, having a projected rotational velocity of 145 km/s. This is giving the star an equatorial bulge that is about 12% wider than the polar diameter.^[9] The star has four^[7] times the mass of the Sun and six times the Sun's girth. It is radiating 247 times the Sun's luminosity from its photosphere at an effective temperature of 9,381 K.^[8]