FN Canis Majoris
Star in Canis Major constellation
From Wikipedia, the free encyclopedia
FN Canis Majoris is a binary star[4] system in the southern constellation Canis Major, near the northern constellation border with Monoceros. It is dimly visible to the naked eye with a combined apparent visual magnitude of 5.41.[3] The system is located at a distance of approximately 3,000 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +31 km/s.[3] It is a runaway star associated with the Sh 2-296 nebula in the CMa OB1 association, and has a conspicuous bow-shock feature.[6]
| Observation data Epoch J2000.0 Equinox ICRS | |
|---|---|
| Constellation | Canis Major |
| Right ascension | 07h 06m 40.76672s[2] |
| Declination | −11° 17′ 38.4396″[2] |
| Apparent magnitude (V) | 5.41[3] (5.69 + 7.04)[4] |
| Characteristics | |
| Spectral type | B0 III/IV[5] or B2 Ia/ab[6] |
| B−V color index | 0.033±0.004[3] |
| Astrometry | |
| Radial velocity (Rv) | +31.0±4.2[3] km/s |
| Proper motion (μ) | RA: −3.14±0.72[2] mas/yr Dec.: +3.32±0.55[2] mas/yr |
| Parallax (π) | 1.07±0.61 mas[2] |
| Distance | approx. 3,000 ly (approx. 900 pc) |
| Details | |
| Mass | 19.23±1.85,[7] 24.0±0.1,[8] 35.5±4.6[9] M☉ |
| Luminosity (bolometric) | 122,079,[7] 690,000[9] L☉ |
| Surface gravity (log g) | 3.59±0.11[9] cgs |
| Temperature | 26,850,[7] 33,600±1,840[9] K |
| Rotational velocity (v sin i) | 100±9[9] km/s |
| Age | 6.0±0.1[8] Myr |
| Other designations | |
| FN CMa, BD−11°1790, GC 9389, HD 53974, HIP 34301, HR 2678, SAO 152394, WDS J07067-1118[10] | |
| Database references | |
| SIMBAD | data |
The brighter component is a visual magnitude 5.69[4] B-type star that has been assigned various stellar classification from B0 III/IV[5] to B2 Ia/ab,[6] suggesting it is an evolved state. In 1967, Graham Hill announced his discovery that the star, then known as HD 53974, is a variable star.[11] It was given its variable star designation, FN Canis Majoris, in 1970.[12] In the past it was classified as a Beta Cephei type variable star[11] with an apparent magnitude that was measured varying between +5.38 and +5.42 over a period of 36.7 hours,[13] but is no longer considered to be one.[14] This is a massive star with estimates ranging from 19[7] to 36[9] times the mass of the Sun, and luminosity estimates of 122,079[7] to 690,000[9] times the Sun's luminosity. The magnitude 7.04[4] companion is located at an angular separation of 0.60″ from the primary at a position angle of 111°, as of 2003.[15]