31 Persei

31 Persei is a single^[13] star in the northern constellation of Perseus. It is visible to the naked eye as a dim, blue-white hued point of light with an apparent visual magnitude of 5.05.^[2] This star is located around 172 parsecs (560 ly) away from the Sun,^[14] and it is drifting closer with a radial velocity of −1.6 km/s.^[5] It is likely a member of the Alpha Persei Cluster.^[15]

31 Persei

Location of 31 Persei (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Perseus
Right ascension	03h 19m 07.63796s[1]
Declination	50° 05′ 41.8724″[1]
Apparent magnitude (V)	5.05[2]
Characteristics
Spectral type	B5V[3]
U−B color index	−0.53[4]
B−V color index	−0.06[4]
Astrometry
Radial velocity (Rv)	−1.60[5] km/s
Proper motion (μ)	RA: +23.580[1] mas/yr Dec.: −23.322[1] mas/yr
Parallax (π)	5.8399±0.1792 mas[1]
Distance	560 ± 20 ly (171 ± 5 pc)
Absolute magnitude (MV)	−1.44[6]
Details
Mass	4.647[7] M☉
Radius	3.4[8] R☉
Luminosity	950[6] L☉
Temperature	15,301[6] K
Metallicity [Fe/H]	0.00[9] dex
Rotational velocity (v sin i)	260[10] km/s
Age	234[11] Myr
Other designations
31 Per, BD+49°902, GC 3945, HD 20418, HIP 15444, HR 989, SAO 38714[12]
Database references
SIMBAD	data

This object is a massive B-type main-sequence star with a stellar classification of B5V^[3] and it is currently generating energy through hydrogen fusion at its core. It is around 234^[9] million years old and is spinning rapidly with a projected rotational velocity of 260 km/s.^[10] The star has 4.6^[7] times the mass of the Sun and about 3.4^[8] times the radius of the Sun. It is radiating 950^[6] times the luminosity of the Sun from its photosphere at an effective temperature of 15,301 K.^[6]