4 Aquilae
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aquila |
| Right ascension | 18h 44m 49.93813s |
| Declination | +02° 03′ 36.1381″ |
| Apparent magnitude (V) | 5.02 |
| Characteristics | |
| Spectral type | B9 V |
| B−V color index | −0.055±0.016 |
| Astrometry | |
| Radial velocity (Rv) | −13.0±4.2 km/s |
| Proper motion (μ) | RA: +9.347 mas/yr Dec.: −14.719 mas/yr |
| Parallax (π) | 6.7299±0.2433 mas |
| Distance | 480 ± 20 ly (149 ± 5 pc) |
| Absolute magnitude (MV) | −0.75 |
| Details | |
| Mass | 3.60±0.06 M☉ |
| Radius | 3.00 R☉ |
| Luminosity | 294+20.4 −20.9 L☉ |
| Surface gravity (log g) | 3.46±0.10 cgs |
| Temperature | 10,965+50 −51 K |
| Rotational velocity (v sin i) | 259 km/s |
| Other designations | |
| 4 Aql, AG+02 2306, BD+01°3766, GC 25652, HD 173370, HIP 91975, HR 7040, SAO 123879 | |
| Database references | |
| SIMBAD | data |
4 Aquilae, abbreviated 4 Aql, is a single, white-hued star in the equatorial constellation of Aquila. 4 Aquilae is the Flamsteed designation. It has an apparent visual magnitude of 5.02, making it a faint star visible to the naked eye. The distance to 4 Aql can be estimated from its annual parallax shift of 6.7 mas, yielding an estimated range of around 480 light years. It is moving closer to the Earth with a heliocentric radial velocity of −13 km/s.
This is a B-type main-sequence star with a stellar classification of B9 V. It was classed as a Be star by Arne Sletteback in 1982, indicating it has ionized circumstellar gas. The star is spinning rapidly, showing a projected rotational velocity of 259 km/s, and is being viewed almost equator-on. It has 3.6 times the mass of the Sun and 3 times the Sun's radius. The star is radiating 294 times the Sun's luminosity from its photosphere at an effective temperature of 10,965 K.