18 Andromedae

18 Andromedae, abbreviated 18 And, is a single^[7] star in the northern constellation of Andromeda. 18 Andromedae is the Flamsteed designation. It is visible to the naked eye with an apparent visual magnitude of 5.350.^[2] The annual parallax shift of 7.9 mas^[1] can be used to estimate a distance of 413 light years. It is moving further from the Earth with a heliocentric radial velocity of +10 km/s.^[5]

18 Andromedae

Location of 18 Andromedae (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Andromeda
Right ascension	23h 39m 08.33195s[1]
Declination	+50° 28′ 18.2328″[1]
Apparent magnitude (V)	5.350[2]
Characteristics
Evolutionary stage	main sequence[3]
Spectral type	B9 Ve[4]
B−V color index	−0.110[2]
Astrometry
Radial velocity (Rv)	+9.9±2.2[5] km/s
Proper motion (μ)	RA: −17.222[1] mas/yr Dec.: −1.739[1] mas/yr
Parallax (π)	7.8893±0.1288 mas[1]
Distance	413 ± 7 ly (127 ± 2 pc)
Details
Mass	3.09±0.06[3] M☉
Luminosity	146.6+14.1 −12.9[3] L☉
Surface gravity (log g)	3.632±0.014[2] cgs
Temperature	10,351±50[2] K
Rotational velocity (v sin i)	183[3] km/s
Other designations
18 And, BD+49°4180, FK5 3897, HD 222304, HIP 116709, HR 8967, SAO 35642, PPM 42060[6]
Database references
SIMBAD	data

This is a B-type main-sequence star with a stellar classification of B9 Ve,^[4] where the 'e' notation indicates this is a Be star. The stellar spectrum of 18 And displays an emission line in the hydrogen Brackett series due to a dense gaseous circumstellar envelope.^[4] The star is spinning rapidly with a projected rotational velocity of 183 km/s and has about three times the mass of the Sun. It is radiating 147 times the Sun's luminosity^[3] from its photosphere at an effective temperature of 10,351 K.^[2]