Eta Lyrae
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Lyra |
| Right ascension | 19h 13m 45.48832s |
| Declination | +39° 08′ 45.4801″ |
| Apparent magnitude (V) | 4.43 |
| Characteristics | |
| Spectral type | B2.5IV |
| B−V color index | −0.150±0.002 |
| Astrometry | |
| Radial velocity (Rv) | −8.1±0.9 km/s |
| Proper motion (μ) | RA: −0.60 mas/yr Dec.: −1.26 mas/yr |
| Parallax (π) | 2.35±0.13 mas |
| Distance | 1,390 ± 80 ly (430 ± 20 pc) |
| Absolute magnitude (MV) | −3.71 |
| Orbit | |
| Period (P) | 56.4±0.5 d |
| Semi-major axis (a) | ≥ 1.841 Gm (0.01231 AU) |
| Eccentricity (e) | 0.53±0.12 |
| Periastron epoch (T) | 2,441,868.4±3.4 JD |
| Argument of periastron (ω) (secondary) | 337±28° |
| Semi-amplitude (K1) (primary) | 2.8±0.5 km/s |
| Details | |
| Mass | 9.97±0.98 M☉ 10.1±1.0 M☉ |
| Radius | 4.3 R☉ |
| Luminosity | 6,605 L☉ |
| Luminosity (bolometric) | 19,095 L☉ |
| Surface gravity (log g) | 3.38 cgs |
| Temperature | 17,360 K 19,525 K |
| Metallicity [Fe/H] | −0.01 dex |
| Rotational velocity (v sin i) | 10 km/s |
| Age | 22.5±2.6 Myr |
| Other designations | |
| Eta Lyr or η Lyr, 20 Lyr, BD+38°3490, HD 180163, HIP 94481, HR 7298, SAO 68010, WDS 19138+3909 | |
| Database references | |
| SIMBAD | data |
Eta Lyrae, a name Latinized from η Lyrae, is a likely binary star system in the northern constellation of Lyra. It has the traditional name Aladfar /əˈlædfɑːr/ and is faintly visible to the naked eye with an apparent visual magnitude of 4.43. The system is located at a distance of approximately 1,390 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −8 km/s.