AR Cephei

AR Cephei (AR Cep) is a variable star in the constellation Cepheus. It is classified as a semiregular star^[7][8] with a spectral type of M4III.^[3]

AR Cephei

AR Cephei, as seen during the Digitized Sky Survey
Observation data Epoch J2000      Equinox J2000
Constellation	Cepheus
Right ascension	22h 51m 33.86137s[1]
Declination	+85° 02′ 46.9418″[1]
Apparent magnitude (V)	6.9 - 8.3[2]
Characteristics
Spectral type	M4 III[3]
B−V color index	+1.52[4]
Variable type	SRb[2]
Astrometry
Radial velocity (Rv)	−15.66±0.23[1] km/s
Proper motion (μ)	RA: 26.580[1] mas/yr Dec.: 4.143[1] mas/yr
Parallax (π)	3.2317±0.0967 mas[1]
Distance	1,010 ± 30 ly (309 ± 9 pc)
Details
Mass	2.8[5] M☉
Radius	123[1] R☉
Luminosity	2,094[1] L☉
Surface gravity (log g)	1.49[5] cgs
Temperature	2,400 - 3,700[citation needed] K
Metallicity [Fe/H]	−0.39[5] dex
Other designations
BD+84 516, HD 217158, HIP 112882, SAO 3809[6]
Database references
SIMBAD	data

Aernout de Sitter discovered the star in 1933.^[3][9] It was given its variable star designation, AR Cephei, in 1939.^[9]

A visual band light curve for AR Cephei, plotted from ASAS-SN data^[10]

AR Cephei is located approximately 1,010 light-years (309 parsecs) from the Solar System, and has a radial velocity of -16 km/s, meaning that it is moving toward the Sun at ~16 kilometers every second.^[1]

See also

• List of variable stars
• T Cephei