Sigma Cassiopeiae
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Cassiopeia |
| σ Cas A | |
| Right ascension | 23h 59m 00.538s |
| Declination | +55° 45′ 17.75″ |
| Apparent magnitude (V) | 5.01 |
| σ Cas B | |
| Right ascension | 23h 59m 00.331s |
| Declination | +55° 45′ 20.37″ |
| Apparent magnitude (V) | 7.24 |
| Characteristics | |
| σ Cas A | |
| Spectral type | B2 IV |
| U−B color index | −0.82 |
| B−V color index | −0.07 |
| Variable type | β Cep |
| σ Cas B | |
| Spectral type | B3 V |
| Astrometry | |
| σ Cas A | |
| Radial velocity (Rv) | −12.6 km/s |
| Proper motion (μ) | RA: +9.956 mas/yr Dec.: −4.492 mas/yr |
| Parallax (π) | 2.7419±0.1491 mas |
| Distance | 1,190 ± 60 ly (360 ± 20 pc) |
| Absolute magnitude (MV) | −3.90 |
| Radial velocity (Rv) | −5.0 km/s |
| Proper motion (μ) | RA: +8.651 mas/yr Dec.: −3.739 mas/yr |
| Parallax (π) | 2.2572±0.0558 mas |
| Distance | 1,440 ± 40 ly (440 ± 10 pc) |
| Absolute magnitude (MV) | −1.7 |
| Details | |
| A | |
| Mass | 12 M☉ |
| Radius | 11.3 R☉ |
| Luminosity | 25,000 L☉ |
| Surface gravity (log g) | 3.6 cgs |
| Temperature | 21,000 K |
| Rotational velocity (v sin i) | 170 km/s |
| Age | 15.8 Myr |
| Other designations | |
| σ Cas, 8 Cassiopeiae, BD+54°3082, HD 224572, HIP 118243, HR 9071, SAO 35947, ADS 17140, CCDM J23591+5546 | |
| Database references | |
| SIMBAD | data |
| A | |
| B | |
Sigma Cassiopeiae is a binary star system in the northern constellation of Cassiopeia. Its name is a Bayer designation that is Latinized from σ Cassiopeiae, and abbreviated Sigma Cas or σ Cas. The pair have a combined apparent magnitude of +4.88, making it visible to the naked eye. Based on Parallax measurements, it is located at a distance of 1,200 to 1,400 light years from Earth.
The primary component, σ Cassiopeiae A, has an apparent magnitude of +5.01 and presents as a subgiant star with a stellar classification of B2 IV. It is a candidate Beta Cephei variable and is rotating rapidly. Its companion, σ Cassiopeiae B, is a main sequence dwarf with a class of B3 V and an apparent magnitude of +7.14. The two stars are three arcseconds apart.