15 Cygni
Star in the constellation Cygnus
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15 Cygni is a single[8] star in the northern constellation Cygnus. With an apparent visual magnitude of 4.90,[2] 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,[1] 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.[5]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cygnus |
| Right ascension | 19h 44m 16.60522s[1] |
| Declination | +37° 21′ 15.6771″[1] |
| Apparent magnitude (V) | 4.90[2] |
| Characteristics | |
| Evolutionary stage | red clump[3] |
| Spectral type | G8 III[2] |
| B−V color index | 0.931[4] |
| Astrometry | |
| Radial velocity (Rv) | −23.62±0.21[5] km/s |
| Proper motion (μ) | RA: +72.660[1] mas/yr Dec.: +35.708[1] mas/yr |
| Parallax (π) | 11.0063±0.1188 mas[1] |
| Distance | 296 ± 3 ly (90.9 ± 1.0 pc) |
| Absolute magnitude (MV) | 0.19[6] |
| Details | |
| Mass | 2.30[4] M☉ |
| Radius | 12[5] R☉ |
| Luminosity | 93.3[4] L☉ |
| Surface gravity (log g) | 2.8[5] cgs |
| Temperature | 4,920±61[4] K |
| Metallicity [Fe/H] | −0.14[5] dex |
| Rotational velocity (v sin i) | 2.8[5] km/s |
| Age | 1.50[4] Gyr |
| Other designations | |
| 15 Cyg, BD+37°3586, FK5 740, HD 186675, HIP 97118, HR 7517, SAO 68778[7] | |
| Database references | |
| SIMBAD | data |
This is an aging giant star with a stellar classification of G8 III,[2] having consumed the hydrogen at its core and evolved off the main sequence. It is a red clump giant,[3] 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,[4] and has expanded to 12 times the Sun's radius.[5] It is radiating 93 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,920 K.[4]