12 Canis Majoris is a variable star located about 707 light years away from the Sun in the southern constellation of Canis Major.[12] It has the variable star designation HK Canis Majoris; 12 Canis Majoris is the Flamsteed designation. This body is just barely visible to the naked eye as a dim, blue-white hued star with a baseline apparent visual magnitude of +6.07.[3] It is moving away from the Earth with a heliocentric radial velocity of +16 km/s.[3] This is the brightest star in the vicinity of the open cluster NGC 2287,[13] although it is probably not a member based on its proper motion.[14]
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Canis Major |
Right ascension | 06h 47m 01.48353s[2] |
Declination | −21° 00′ 55.4517″[2] |
Apparent magnitude (V) | +6.07[3] |
Characteristics | |
Spectral type | B7 II/III[4] or B5 V[5] |
B−V color index | −0.159±0.004[3] |
Variable type | SX Ari[6] |
Astrometry | |
Radial velocity (Rv) | +16.4±2.5[3] km/s |
Proper motion (μ) | RA: −14.568[2] mas/yr Dec.: +5.778[2] mas/yr |
Parallax (π) | 4.6155 ± 0.0543 mas |
Distance | 707 ± 8 ly (217 ± 3 pc) |
Absolute magnitude (MV) | −0.81[3] |
Details | |
Mass | 4.8[7] M☉ |
Radius | 2.73[8] R☉ |
Luminosity | 537[9] L☉ |
Surface gravity (log g) | 4.23[5] cgs |
Temperature | 15,830±60[9] K |
Metallicity [Fe/H] | −0.37[10] dex |
Rotation | 2.18045 d[7] |
Rotational velocity (v sin i) | 65[7] km/s |
Age | 134[11] Myr |
Other designations | |
Database references | |
SIMBAD | data |
This star has a stellar classification of B7 II/III,[4] matching the spectrum of a B-type star intermediate between a giant and bright giant.[4] (Cidale et al. (2007) show a class of B5 V,[5] which would indicate it is instead a B-type main-sequence star.) It is a magnetic Bp star[15] of the helium–weak variety (CP4), with the spectrum displaying evidence for vertical stratification of helium in the atmosphere.[16] Samus et al. (2017) classify it as an SX Arietis variable that varies in brightness by about 0.05 magnitudes over a period of 2.18045 days.[6] It has 4.8 times the mass of the Sun and 2.73[8] times the Sun's radius. The star is radiating 537 times the Sun's luminosity from its photosphere at an effective temperature of 15,830 K.