Theta Canis Majoris
Star in the constellation Canis Major
From Wikipedia, the free encyclopedia
Theta Canis Majoris is a solitary,[9] orange-hued star near the northern edge[10] of the constellation Canis Major, forming the nose of the "dog".[11] Its name is a Bayer designation that is Latinized from θ Canis Majoris, and abbreviated Theta CMa or θ CMa. The star is visible to the naked eye with an apparent visual magnitude of 4.08.[2] Based upon an annual parallax shift of 12.07 mas as seen from Earth,[1] it is located about 270 light years distant. The star is moving away from the Sun with a radial velocity of +96.2 km/s.[5]
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Canis Major |
| Right ascension | 06h 54m 11.399s[1] |
| Declination | â12° 02â² 19.06â³[1] |
| Apparent magnitude (V) | 4.08[2] |
| Characteristics | |
| Evolutionary stage | Red giant branch[3] |
| Spectral type | K4 III[2] |
| UâB color index | +1.69[4] |
| BâV color index | +1.43[4] |
| Astrometry | |
| Radial velocity (Rv) | +96.2±0.1[5] km/s |
| Proper motion (μ) | RA: â136.454 mas/yr[1] Dec.: â14.322 mas/yr[1] |
| Parallax (Ï) | 12.0676±0.62 mas[1] |
| Distance | 270 ± 10 ly (83 ± 4 pc) |
| Absolute magnitude (MV) | â0.36±0.15[6] |
| Details[5] | |
| Mass | 0.95±0.03 Mâ |
| Radius | 33.01±0.75[7] Râ |
| Luminosity | 304.9±7[7] Lâ |
| Surface gravity (log g) | 1.67±0.08 cgs |
| Temperature | 4,196±43[7] K |
| Metallicity [Fe/H] | â0.52±0.04 dex |
| Rotational velocity (v sin i) | 2.72±0.40 km/s |
| Age | 10.41±1.31 Gyr |
| Other designations | |
| θ CMa, 14 Canis Majoris, BDâ11°1681, FK5 266, GC 9051, HD 50778, HIP 33160, HR 2574, SAO 152071[8] | |
| Database references | |
| SIMBAD | data |
This is a evolved K-type giant star with a stellar classification of K4 III,[2] having exhausted the supply of hydrogen at its core then expanded. Theta Canis Majoris is 5% less massive than the Sun,[5] but has grown to 33 times the Sun's girth.[7] This star is around ten billion years old,[5] over twice the age of the Solar System.[12] It radiates 305 times the Sun's luminosity from its expanded photosphere at an effective temperature of 4,200 K.[7] This temperature gives it the cool orange hue of a K-type star.[13]