15 Andromedae, abbreviated 15 And, is a single,[10] variable star[7] in the northern constellation of Andromeda. 15 Andromedae is the Flamsteed designation, while its variable star designation is V340 And.[9] Its apparent visual magnitude is 5.55,[3] which indicates it is faintly visible to the naked eye. Its estimated distance from the Earth is 252 light years, and it is moving further away with a heliocentric radial velocity of 13 km/s.[3]
Observation data Epoch J2000.0 Equinox J2000.0 | |
---|---|
Constellation | Andromeda |
Right ascension | 23h 34m 37.53652s[2] |
Declination | +40° 14′ 11.1795″[2] |
Apparent magnitude (V) | 5.55[3] |
Characteristics | |
Spectral type | A1 III,[4] A1 Va,[5] or kA1hA3mA0.5 Va+.[6] |
U−B color index | 0.08 |
B−V color index | 0.096±0.005[3] |
Variable type | δ Sct[7] |
Astrometry | |
Radial velocity (Rv) | 13.1±0.6[3] km/s |
Proper motion (μ) | RA: -18.165 mas/yr Dec.: −46.183[2] mas/yr |
Parallax (π) | 12.9406 ± 0.0973 mas[2] |
Distance | 252 ± 2 ly (77.3 ± 0.6 pc) |
Absolute magnitude (MV) | +1.16±0.16[8] |
Details[4] | |
Mass | 2.7 M☉ |
Luminosity | 27 L☉ |
Surface gravity (log g) | 3.90±0.03[8] cgs |
Temperature | 9,225 K |
Rotational velocity (v sin i) | 105[8] km/s |
Age | 130 Myr |
Other designations | |
Database references | |
SIMBAD | data |
Depending on the source, this star has been classified as a giant star with a stellar classification of A1 III,[4] an A-type main-sequence star with a class of A1 Va,[5] or a Lambda Boötis star with a class of kA1hA3mA0.5 Va+.[6] It is a Delta Scuti variable that changes in brightness by 0.03 magnitude.[7] Two variability cycles, with periods 0.0403 and 0.0449 days, have been observed, a common feature for Lambda Boötis stars.[11] The star is around 130[4] million years old and has a high rotation rate, showing a projected rotational velocity of 105 km/s.[8] It has 2.7 times the mass of the Sun and is radiating 27 times the Sun's luminosity from its photosphere at an effective temperature of 9,225 K.[4]
This system has an excess emission of infrared radiation that suggests the presence of an orbiting disk of dust at a distance of around 50 AU from the host star.[4]