Pi1 Cygni
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Cygnus |
| Right ascension | 21h 42m 05.66458s |
| Declination | +51° 11′ 22.6415″ |
| Apparent magnitude (V) | 4.66 |
| Characteristics | |
| Spectral type | B3 IV |
| B−V color index | −0.11 |
| Astrometry | |
| Proper motion (μ) | RA: +5.29 mas/yr Dec.: −1.78 mas/yr |
| Parallax (π) | 1.89±0.15 mas |
| Distance | 1,700 ± 100 ly (530 ± 40 pc) |
| Absolute magnitude (MV) | −3.91 |
| Orbit | |
| Period (P) | 26.33 d |
| Eccentricity (e) | 0.00 |
| Periastron epoch (T) | 2431306.5 ± 10.0 JD |
| Argument of periastron (ω) (secondary) | 0.00° |
| Semi-amplitude (K1) (primary) | 16.5 km/s |
| Details | |
| π1 Cyg A | |
| Mass | 10.1±0.1 M☉ |
| Radius | 5.6 R☉ |
| Luminosity | 16,538 L☉ |
| Temperature | 18,360±1,100 K |
| Rotational velocity (v sin i) | 55 km/s |
| Age | 25.1±0.8 Myr |
| Other designations | |
| π1 Cyg, 80 Cygni, BD+50°3410, FK5 3733, HD 206672, HIP 107136, HR 8301, SAO 33665. | |
| Database references | |
| SIMBAD | data |
Pi1 Cygni (π1 Cygni, abbreviated Pi1 Cyg, π1 Cyg) is a binary star in the northern constellation of Cygnus. It is visible to the naked eye, having a combined apparent visual magnitude of 4.66. The distance to this system can be roughly gauged by its annual parallax shift of 1.89 mas, which yields a separation of around 1,700 light years from the Sun, give or take a hundred light years.
The two components are designated Pi1 Cygni A (officially named Azelfafage /əˈzɛlfəfeɪdʒ/, the traditional name for the system) and B.