Alpha Cassiopeiae

α Cassiopeiae

Location of α Cassiopeiae (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Cassiopeia
Right ascension	00h 40m 30.4411s[1]
Declination	+56° 32′ 14.392″[1]
Apparent magnitude (V)	2.240[2]
Characteristics
Spectral type	K0-IIIa[3]
U−B color index	1.14[4]
B−V color index	1.16[4]
Variable type	Suspected[5]
Astrometry
Radial velocity (Rv)	−4.31 km/s
Proper motion (μ)	RA: 50.88[1] mas/yr Dec.: −32.13[1] mas/yr
Parallax (π)	14.29 ± 0.15 mas[1]
Distance	228 ± 2 ly (70.0 ± 0.7 pc)
Absolute magnitude (MV)	−2.01[6]
Details[7]
Mass	3.98 M☉
Radius	45.03+1.57 −1.68[8] R☉
Luminosity	734±52[8] L☉
Surface gravity (log g)	1.73 cgs
Temperature	4476±15[8] K
Metallicity [Fe/H]	–0.2 dex
Rotational velocity (v sin i)	6.71[9] km/s
Age	220 Myr
Other designations
Schedar, α Cas, Alpha Cas, 18 Cas, BD+55°139, FK5 21, GC 792, HD 3712, HIP 3179, HR 168, SAO 21609, ADS 561, CCDM J00405+5632, WDS J00405+5632
Database references
SIMBAD	data

Alpha Cassiopeiae or α Cassiopeiae, also named Schedar (/ˈʃɛdɑːr/),^[10][11] is a second-magnitude star in the northern constellation of Cassiopeia. Though listed as the "alpha star" by Johann Bayer, α Cas's visual brightness closely matches the 'beta' (β) star in the constellation (Beta Cassiopeiae) and it may appear marginally brighter or dimmer, depending on which passband is used. However, recent calculations from NASA's WISE telescope confirm that α Cas is the brightest in Cassiopeia, with an apparent magnitude of 2.240. Its absolute magnitude is 18 times greater than β Cas, and it is located over four times farther away from the Sun.