15 Cygni
15 Cygni is a single star in the northern constellation Cygnus. With an apparent visual magnitude of 4.90, it is a faint star but visible to the naked eye. The distance to 15 Cygni can be estimated from its annual parallax shift of 11.0 mas, which yields a separation of some 296 light years. It is moving closer to the Sun with a heliocentric radial velocity of −23.6 km/s.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cygnus |
| Right ascension | 19h 44m 16.60522s |
| Declination | +37° 21′ 15.6771″ |
| Apparent magnitude (V) | 4.90 |
| Characteristics | |
| Spectral type | G8 III |
| B−V color index | 0.931 |
| Astrometry | |
| Radial velocity (Rv) | −23.62±0.21 km/s |
| Proper motion (μ) | RA: +72.660 mas/yr Dec.: +35.708 mas/yr |
| Parallax (π) | 11.0063 ± 0.1188 mas |
| Distance | 296 ± 3 ly (90.9 ± 1.0 pc) |
| Absolute magnitude (MV) | 0.19 |
| Details | |
| Mass | 2.30 M☉ |
| Radius | 12 R☉ |
| Luminosity | 93.3 L☉ |
| Surface gravity (log g) | 2.8 cgs |
| Temperature | 4,920±61 K |
| Metallicity [Fe/H] | −0.14 dex |
| Rotational velocity (v sin i) | 2.8 km/s |
| Age | 1.50 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
This is an aging giant star with a stellar classification of G8 III, having consumed the hydrogen at its core and evolved off the main sequence. It is a red clump giant, which means it is generating energy via helium fusion at its core. The star is 1.50 billion years old with 2.3 times the mass of the Sun, and has expanded to 12 times the Sun's radius. It is radiating 93 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,920 K.