Theta Aquilae
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aquila |
| Right ascension | 20h 11m 18.28528s |
| Declination | −00° 49′ 17.2626″ |
| Apparent magnitude (V) | 3.26 |
| Characteristics | |
| Spectral type | B9.5 III + B9.5 III |
| U−B color index | −0.15 |
| B−V color index | −0.07 |
| Variable type | Stable |
| Astrometry | |
| Radial velocity (Rv) | −27.3 km/s |
| Proper motion (μ) | RA: +35.26 mas/yr Dec.: +5.71 mas/yr |
| Parallax (π) | 11.39±0.24 mas |
| Distance | 286 ± 6 ly (88 ± 2 pc) |
| Absolute magnitude (MV) | −1.39/+0.14 |
| Orbit | |
| Period (P) | 17.124281±0.000038 d |
| Semi-major axis (a) | 3.148±0.002 mas″ |
| Eccentricity (e) | 0.6040±0.0009 |
| Inclination (i) | 144.10±0.18° |
| Longitude of the node (Ω) | 96.92±0.19° |
| Periastron epoch (T) | 2458624.154±0.004 JD |
| Argument of periastron (ω) (primary) | 33.73±0.22° |
| Semi-amplitude (K1) (primary) | 48.78±0.09 km/s |
| Semi-amplitude (K2) (secondary) | 63.48±0.11 km/s |
| Details | |
| θ Aql A | |
| Mass | 3.564±0.049 M☉ |
| Radius | 4.76±0.14 R☉ |
| Luminosity | 229.8±22.5 L☉ |
| Surface gravity (log g) | 3.64±0.02 cgs |
| Temperature | 10,300±200 K |
| Metallicity [Fe/H] | +0.20 dex |
| Rotational velocity (v sin i) | 36.3±0.4 km/s |
| Age | 215 Myr |
| θ Aql B | |
| Mass | 2.739±0.037 M☉ |
| Radius | 2.34±0.07 R☉ |
| Luminosity | 54.0±5.8 L☉ |
| Surface gravity (log g) | 4.14±0.02 cgs |
| Temperature | 10,230±220 K |
| Rotational velocity (v sin i) | 13.6±0.9 km/s |
| Other designations | |
| Antinous, Theta Aql, θ Aquilae, θ Aql, 65 Aql, BD−01 3911, FK5 756, GC 28010, HD 191692, HIP 99473, HR 7710, SAO 144150, PPM 180896, WDS J20113-0049A | |
| Database references | |
| SIMBAD | data |
Theta Aquilae, also named Antinous, is a binary star in the equatorial constellation Aquila. Its identifier is a Bayer designation that is Latinized from θ Aquilae, and abbreviated Theta Aql or θ Aql. The combined apparent visual magnitude of the pair is 3.26, making it the fourth-brightest member of the constellation. This distance to this system can be determined through the parallax technique, yielding an estimate of roughly 286 light-years (88 parsecs) from Earth. It is drifting closer with a heliocentric radial velocity of −27 km/s.