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]
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 | |
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[3] km/s and has about three[3] times the mass of the Sun. It is radiating 147[3] times the Sun's luminosity from its photosphere at an effective temperature of 10,351 K.[2]