18 Andromedae
Blue-hued star in the constellation Andromeda
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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 7.8 mas[1] can be used to estimate a distance of 419 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 08.33166s[1] |
| Declination | +50° 28â² 18.2375â³[1] |
| Apparent magnitude (V) | 5.350[2] |
| Characteristics | |
| Evolutionary stage | main sequence[3] |
| Spectral type | B9 Ve[4] |
| BâV color index | â0.110[2] |
| Astrometry | |
| Radial velocity (Rv) | +9.9±2.2[5] km/s |
| Proper motion (μ) | RA: â17.057[1] mas/yr Dec.: â2.041[1] mas/yr |
| Parallax (Ï) | 7.7914±0.0633 mas[1] |
| Distance | 419 ± 3 ly (128 ± 1 pc) |
| Details | |
| Mass | 3.09±0.06[3] Mâ |
| Radius | 3.61±0.08[1] Râ |
| Luminosity | 146.6+14.1 â12.9[3] Lâ |
| 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] The star has about 3.61 times the radius of the Sun.[1]