12 Cassiopeiae

12 Cassiopeiae (12 Cas) is a white giant in the constellation Cassiopeia, about 860 light years away. It has an apparent magnitude of 5.4, so it faintly visible to the naked eye.

12 Cassiopeiae

Location of 12 Cassiopeiae (circled)
Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Cassiopeia[1]
Right ascension	00h 24m 47.5055s[2]
Declination	+61° 49′ 51.808″[2]
Apparent magnitude (V)	+5.377[3]
Characteristics
Spectral type	B9III[4]
U−B color index	−0.16[5]
B−V color index	+0.00[5]
Astrometry
Radial velocity (Rv)	−1.76±0.60[2] km/s
Proper motion (μ)	RA: +14.126[2] mas/yr Dec.: −2.715[2] mas/yr
Parallax (π)	3.8102±0.0612 mas[2]
Distance	860 ± 10 ly (262 ± 4 pc)
Absolute magnitude (MV)	−1.27[1]
Details
Mass	3.1[6] M☉
Radius	5.7[7] R☉
Luminosity	386[7] L☉
Surface gravity (log g)	2.94[6] cgs
Temperature	10,728[7] K
Metallicity [Fe/H]	−0.96[6] dex
Rotational velocity (v sin i)	155[8] km/s
Age	257[9] Myr
Other designations
12 Cas, HR 93, HD 2011, BD+61°69, HIP 1960
Database references
SIMBAD	data

The spectrum of 12 Cassiopeiae is classified as a B9-type giant. About three times as massive as the Sun and 386 times as luminous, it has expanded away from the main sequence after exhausting its core hydrogen. It now has a radius of 5.7 R_☉ with an effective temperature of about 10,728 K, leading to a bolometric luminosity of 386 L_☉.