71 Aquilae
71 Aquilae (abbreviated 71 Aql) is a binary star in the equatorial constellation of Aquila. 71 Aquilae is its Flamsteed designation though it also bears the Bayer designation l Aquilae. The apparent visual magnitude of the system is 4.33, making it bright enough to be viewed by the naked eye. It has an annual parallax shift of 9.67 mas, which equates to a physical distance of 340 light-years (100 parsecs) from Earth, give or take a 30 light-year margin of error. At this distance, the brightness of the system is diminished by 0.065 in visual magnitude from extinction caused by interstellar gas and dust.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aquila |
| Right ascension | 20h 38m 20.28206s |
| Declination | −01° 06′ 18.4311″ |
| Apparent magnitude (V) | 4.33 |
| Characteristics | |
| Spectral type | G8 III |
| U−B color index | +0.68 |
| B−V color index | +0.96 |
| R−I color index | 0.46 |
| Astrometry | |
| Radial velocity (Rv) | -5.6 km/s |
| Proper motion (μ) | RA: +14.84 mas/yr Dec.: -16.45 mas/yr |
| Parallax (π) | 9.67 ± 0.75 mas |
| Distance | 340 ± 30 ly (103 ± 8 pc) |
| Absolute magnitude (MV) | –1.03 |
| Orbit | |
| Period (P) | 205.2 days |
| Semi-major axis (a) | 3.82 ± 0.81 mas |
| Eccentricity (e) | 0.000 |
| Inclination (i) | 147.70° ± 5.90° |
| Longitude of the node (Ω) | 314.00 ± 1.30° |
| Periastron epoch (T) | 2423358.0 HJD |
| Argument of periastron (ω) (secondary) | 0.00° |
| Details | |
| Surface gravity (log g) | 2.87 cgs |
| Temperature | 5,060 K |
| Metallicity [Fe/H] | –0.13 dex |
| Rotational velocity (v sin i) | 10 km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
This is a spectroscopic binary system where the presence of an orbiting companion is revealed by shifts in the spectral lines caused by the Doppler effect. The primary component is a giant star with a stellar classification of G8 III. The secondary is following a circular orbit with a period of 205.2 days.