Gamma Cassiopeiae
Gamma Cassiopeiae, Latinized from γ Cassiopeiae, is a bright star at the center of the distinctive "W" asterism in the northern circumpolar constellation of Cassiopeia. Although it is a fairly bright star with an apparent visual magnitude that varies from 1.6 to 3.0, it has no traditional Arabic or Latin name. It sometimes goes by the informal name Navi. It was observed 1866 by Angelo Secchi, the first star ever observed with emission lines. It is now considered a Be star.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cassiopeia |
| Right ascension | 00h 56m 42.50108s |
| Declination | +60° 43′ 00.2984″ |
| Apparent magnitude (V) | 2.47 (1.6 - 3.0) |
| Characteristics | |
| Spectral type | B0.5IVe |
| U−B color index | −1.08 |
| B−V color index | −0.15 |
| Variable type | γ Cas |
| Astrometry | |
| Radial velocity (Rv) | −6.8 km/s |
| Proper motion (μ) | RA: +25.17 mas/yr Dec.: −3.92 mas/yr |
| Parallax (π) | 5.94 ± 0.12 mas |
| Distance | 550 ± 10 ly (168 ± 3 pc) |
| Absolute magnitude (MV) | −3.98 |
| Orbit | |
| Primary | Aa |
| Companion | Ab |
| Period (P) | 203.523±0.076 d |
| Eccentricity (e) | 0 |
| Inclination (i) | 45° |
| Semi-amplitude (K1) (primary) | 4.297±0.090 km/s |
| Orbit | |
| Primary | Aab |
| Companion | Ac |
| Period (P) | 60.0 yr |
| Semi-major axis (a) | 0.15″ |
| Details | |
| Aa | |
| Mass | 13 M☉ |
| Radius | 10 R☉ |
| Luminosity | 34,000 L☉ |
| Surface gravity (log g) | 3.50 cgs |
| Temperature | 25,000 K |
| Rotational velocity (v sin i) | 432 km/s |
| Age | 8.0±0.4 Myr |
| Ab | |
| Mass | 0.98 M☉ |
| Other designations | |
| Database references | |
| SIMBAD | data |
Gamma Cassiopeiae is also a variable star and a multiple star system. Based upon parallax measurements made by the Hipparcos satellite, it is located at a distance of roughly 550 light-years from Earth. Together with its common-proper-motion companion, HD 5408, the system could contain a total of eight stars.