Delta Cygni
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cygnus |
| Right ascension | 19h 44m 58.47854s |
| Declination | +45° 07′ 50.9161″ |
| Apparent magnitude (V) | 2.87 |
| Characteristics | |
| Spectral type | A0 IV (B9 III + F1 V) |
| U−B color index | −0.10 |
| B−V color index | −0.02 |
| Variable type | Suspected |
| Astrometry | |
| Radial velocity (Rv) | −20.1 km/s |
| Proper motion (μ) | RA: +44.07 mas/yr Dec.: +48.66 mas/yr |
| Parallax (π) | 19.77±0.48 mas |
| Distance | 165 ± 4 ly (51 ± 1 pc) |
| Absolute magnitude (MV) | −0.74 |
| Orbit | |
| Primary | A |
| Companion | B |
| Period (P) | 780.27 yr |
| Semi-major axis (a) | 3.0″ |
| Eccentricity (e) | 0.4670 |
| Details | |
| Mass | 2.93 M☉ |
| Radius | 4.81±0.36 R☉ |
| Luminosity | 155 L☉ |
| Surface gravity (log g) | 3.4±0.25 cgs |
| Temperature | 10400±400 K |
| Rotational velocity (v sin i) | 142 km/s |
| Other designations | |
| Fawaris, δ Cyg, 18 Cygni, 18 Cyg, BD+44°3234, HD 186882, HIP 97165, HR 7528, SAO 48796, WDS J19450+4508AB | |
| Database references | |
| SIMBAD | data |
Delta Cygni is a binary star of a combined third-magnitude in the constellation of Cygnus. It is also part of the Northern Cross asterism whose brightest star is Deneb. Its name is a Bayer designation that is Latinized from δ Cygni, and abbreviated Delta Cyg or δ Cyg. Based upon parallax measurements obtained during the Hipparcos mission, Delta Cygni is located roughly 165 light-years (51 parsecs) distant from the Sun.
Delta Cygni's two components are designated Delta Cygni A (officially named Fawaris /fəˈwɛərɪs/) and B. More widely separated is a faint third component, a 12th magnitude star that is moving along with the others. Together they form a triple star system.