Kappa Cygni
Kappa Cygni, Latinized from κ Cygni, is a star in the northern constellation of Cygnus. It has an apparent visual magnitude of 3.8, which is bright enough to be seen with the naked eye. In the constellation, it forms the tip of Cygnus's left wing. The radiant of the minor Kappa Cygnids meteor shower is located about 5° north of this star.
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Cygnus |
| Right ascension | 19h 17m 06.16865s |
| Declination | +53° 22′ 06.4534″ |
| Apparent magnitude (V) | 3.814 |
| Characteristics | |
| Spectral type | G9 III |
| U−B color index | +0.767 |
| B−V color index | +0.965 |
| Astrometry | |
| Radial velocity (Rv) | –29.3 km/s |
| Proper motion (μ) | RA: +60.07 mas/yr Dec.: +122.83 mas/yr |
| Parallax (π) | 26.27 ± 0.10 mas |
| Distance | 124.2 ± 0.5 ly (38.1 ± 0.1 pc) |
| Absolute magnitude (MV) | +0.90 |
| Details | |
| Radius | 8–9 R☉ |
| Luminosity | 51 L☉ |
| Surface gravity (log g) | 2.7 cgs |
| Temperature | 4,920 K |
| Metallicity [Fe/H] | 0.13 ± 0.07 dex |
| Rotational velocity (v sin i) | 3.7 km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
Examination of this star's spectrum show it to match a stellar classification of G9 III, with the 'III' luminosity class revealing that it has consumed the hydrogen fuel at its core and expanded into the giant star stage of its stellar evolution. It is known to vary in luminosity, but only by about 0.01 to 0.02 magnitudes. The measured angular diameter of this star, after correction for limb darkening, is 2.07 ± 0.09 mas. At an estimated distance of 124.2 light-years (38.1 parsecs) based on parallax measurements, this yields a physical size of about 8–9 times the radius of the Sun. The outer envelope has an effective temperature of 4,920 K, giving it the yellow-orange hue of a star near the transition from a G- to a K-type classification.