Sigma Cassiopeiae

Not to be confused with S Cassiopeiae.
σ Cassiopeiae
Location of σ Cassiopeiae (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Cassiopeia
σ Cas A
Right ascension 23h 59m 00.538s[1]
Declination +55° 45′ 17.75″[1]
Apparent magnitude (V) 5.01[2]
σ Cas B
Right ascension 23h 59m 00.331s[3]
Declination +55° 45′ 20.37″[3]
Apparent magnitude (V) 7.24[2]
Characteristics
σ Cas A
Spectral type B2 IV[4]
U−B color index −0.82
B−V color index −0.07
Variable type β Cep?[5]
σ Cas B
Spectral type B3 V[4]
Astrometry
σ Cas A
Radial velocity (Rv)−12.6[6] km/s
Proper motion (μ) RA: +9.956[1] mas/yr
Dec.: −4.492[1] mas/yr
Parallax (π)2.7419 ± 0.1491 mas[1]
Distance1,190 ± 60 ly
(360 ± 20 pc)
Absolute magnitude (MV)−3.90[5]
Radial velocity (Rv)−5.0[6] km/s
Proper motion (μ) RA: +8.651[3] mas/yr
Dec.: −3.739[3] mas/yr
Parallax (π)2.2572 ± 0.0558 mas[3]
Distance1,440 ± 40 ly
(440 ± 10 pc)
Absolute magnitude (MV)−1.7[4]
Details[5]
A
Mass12 M☉
Radius11.3 R☉
Luminosity25,000 L☉
Surface gravity (log g)3.6 cgs
Temperature21,000 K
Rotational velocity (v sin i)170 km/s
Age15.8 Myr
Other designations
8 Cassiopeiae, HR 9071, HD 224572, BD+54°3082, HIP 118243, SAO 35947, ADS 17140, CCDM J23591+5546
Database references
SIMBADdata
σ Cassiopeiae in optical light

Sigma Cassiopeiae (σ Cas, σ Cassiopeiae) is a binary star in the constellation Cassiopeia. It is 1,200 to 1,400 light years from Earth and has a combined apparent magnitude of +4.88.[7]

The primary component, σ Cassiopeiae A, is a B2 subgiant with an apparent magnitude of +5.0. Its companion, σ Cassiopeiae B, is a B5 main sequence dwarf with an apparent magnitude of +7.1. The two stars are three arcseconds apart.[8]

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