Chi Cygni
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cygnus |
| Right ascension | 19h 50m 33.92439s |
| Declination | +32° 54′ 50.6097″ |
| Apparent magnitude (V) | 3.3 – 14.2 |
| Characteristics | |
| Spectral type | S6+/1e = MS6+ (S6,2e – S10,4e) |
| U−B color index | −0.30 – +0.98 |
| B−V color index | +1.56 – +2.05 |
| Variable type | Mira |
| Astrometry | |
| Radial velocity (Rv) | +1.60 km/s |
| Proper motion (μ) | RA: -20.16 mas/yr Dec.: -38.34 mas/yr |
| Parallax (π) | 5.53±1.10 mas |
| Distance | 553 ly (169 pc) |
| Absolute magnitude (MV) | −3.2 – +7.7 |
| Details | |
| Mass | 2.1+1.5 −0.7 M☉ |
| Radius | 348 – 480 R☉ |
| Luminosity | 6,000 – 9,000 L☉ |
| Surface gravity (log g) | 0.49 cgs |
| Temperature | 2,441 – 2,742 K |
| Metallicity [Fe/H] | -1.00 dex |
| Other designations | |
| χ Cyg, Chi Cyg, HD 187796, BD+32°3593, HIP 97629, HR 7564, SAO 68943 | |
| Database references | |
| SIMBAD | data |
Chi Cygni is a Mira variable star in the constellation Cygnus, and also an S-type star. Its name is a Bayer designation that is Latinized from χ Cygni, and abbreviated Chi Cyg or χ Cyg. It is around 500 light years away.
χ Cygni is an asymptotic giant branch star, a very cool and luminous red giant nearing the end of its life. It was discovered to be a variable star in 1686 and its apparent visual magnitude varies from as bright as 3.3 to as dim as 14.2, corresponding to a brightness factor of over 20,000. It is only visible to the naked eye for a short period near each maximum.