Zeta Aquilae
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aquila |
| Right ascension | 19h 05m 24.60802s |
| Declination | +13° 51′ 48.5182″ |
| Apparent magnitude (V) | 2.983 |
| Characteristics | |
| Spectral type | A0 Vn |
| U−B color index | +0.080 |
| B−V color index | +0.009 |
| Astrometry | |
| Radial velocity (Rv) | −25 km/s |
| Proper motion (μ) | RA: −0.25 mas/yr Dec.: −95.56 mas/yr |
| Parallax (π) | 39.28±0.16 mas |
| Distance | 83.0 ± 0.3 ly (25.5 ± 0.1 pc) |
| Absolute magnitude (MV) | +0.96 |
| Details | |
| A | |
| Mass | 2.53±0.16 M☉ |
| Radius | 2.762 (equatorial) 2.148 (polar) R☉ |
| Luminosity | 52.5+2.5 −2.4 L☉ |
| Surface gravity (log g) | 3.60 (equatorial) 4.15 (polar) cgs |
| Temperature | 8,680 (equatorial) 10,952 (polar) K |
| Metallicity [Fe/H] | −0.52±0.04 dex |
| Rotation | 10.575 hours |
| Rotational velocity (v sin i) | 306+20 −5 km/s |
| Age | 100±50 Myr |
| B | |
| Mass | 0.50 M☉ |
| Other designations | |
| Okab (primary), Zeta Aql, ζ Aql, 17 Aql, BD+13 3899, FK5 716, GJ 4095, HD 177724, HIP 93747, HR 7235, SAO 104461, WDS J19054+1352A | |
| Database references | |
| SIMBAD | data |
Zeta Aquilae is a binary star system in the equatorial constellation of Aquila. Its name is a Bayer designation that is Latinized from ζ Aquilae, and abbreviated Zeta Aql or ζ Aql. This system is readily visible with the naked eye as a point of light, having a combined apparent visual magnitude of 2.983. Based on parallax measurements obtained during the Hipparcos mission, it is approximately 83 light-years (25 parsecs) distant from the Sun. It is a candidate member of the TW Hydrae association of co-moving stars.
Zeta Aquilae's two components can be designated Zeta Aquilae A and B. The former is officially named Okab, pronounced /ˈoʊkæb/, the traditional name for the system. Zeta Aquilae has a number of companions listed and together they are designated WDS J19054+1352. As the primary star of this group, Zeta Aquilae also bears the designation WDS J19054+1352A. The companions are then designated WDS J19054+1352B, C, D and E.