| |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Canis Major |
| Right ascension | 07h14m 15.21192s[3] |
| Declination | −26° 21′ 09.0312″[3] |
| Apparent magnitude (V) | +4.65[4] (+4.92 + 5.39)[5] |
| Characteristics | |
| Spectral type | B3 IIIpe[6] |
| B−V color index | −0.17±0.16[7] |
| Variable type | γ Cas + β Cep:[8] |
| Astrometry | |
| Radial velocity (Rv) | 16.3±3.6[7] km/s |
| Proper motion (μ) | RA: −6.91[3] mas/yr Dec.: +3.17[3] mas/yr |
| Parallax (π) | 1.88 ± 0.32 mas[3] |
| Distance | approx. 1,700 ly (approx. 530 pc) |
| Absolute magnitude (MV) | −4.13[7] |
| Orbit[9] | |
| Period (P) | 118.54±11.14 yr |
| Semi-major axis (a) | 0.178±0.012″ |
| Eccentricity (e) | 0.747±0.094 |
| Inclination (i) | 80.2±1.0° |
| Longitude of the node (Ω) | 131.3±3.0° |
| Periastron epoch (T) | 1,971.01±0.74 |
| Argument of periastron (ω) (secondary) | 85.0±3.6° |
| Details | |
| 27 CMa A | |
| Mass | 12.5±2.5[10] M☉ |
| Luminosity (bolometric) | 15,610[4] L☉ |
| Surface gravity (log g) | 3.514[11] cgs |
| Temperature | 21,061[11] K |
| Rotational velocity (v sin i) | 290[11] km/s |
| Age | 0.1±0.1[10] Myr |
| Other designations | |
27 CMa, EW Canis Majoris, BD−26°4057, GC 9608, HD 56014, HIP 34981, HR 2745, SAO 173264, CCDM J07143-2621, WDS J07143-2621[12] | |
| Database references | |
| SIMBAD | data |
27 Canis Majoris is a binary star[5] system in the northern constellationofCanis Major,[12] located approximately 1,700 light years away from the Sun.[3] It has the variable star designation EW Canis Majoris;[8] 27 Canis Majoris is the Flamsteed designation. This system is visible to the naked eye as a dim, blue-white hued star with an apparent visual magnitude of +4.65.[4] It is moving away from the Earth with a heliocentric radial velocity of 16 km/s.[7]
The pair of stars in this system were first resolved by W. S. Finsen in 1953, and the split has been widening since that time.[13] The system has an orbital period of around 119 years with an eccentricity of 0.7 and a semimajor axisof0.178″.[9] The magnitude 4.92[5] primary, designated component A, is a Be star with a stellar classification of B3 IIIpe.[6] It is spinning rapidly with a projected rotational velocity of 290 km/s, compared to a critical velocity of 389 km/s.[11] The star appears to be a Beta Cephei variable[14] with a pulsation period of 0.0919 days and an amplitude of 0.0080 in magnitude.[15]
The magnitude 5.39[5] secondary, component B, is classified as a Gamma Cassiopeiae type variable star. Due to its variable nature, the brightness of the system varies from magnitude +4.42 to +4.82.[8]
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