Xi2 Canis Majoris
Star in the constellation Canis Major
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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]
 | |
| 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]