68 Cygni
Star in the constellation Cygnus / From Wikipedia, the free encyclopedia
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68 Cygni is the Flamsteed designation for a star in the constellation Cygnus. Located approximately 690 parsecs (2,300 ly) distant, the star is a hot blue giant of spectral type O7.5IIIn((f)), a massive star that is likely currently expanding to become a supergiant. The star is surrounded by a ring-shaped nebula (likely a Strömgren sphere) named S 119.
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Cygnus |
Right ascension | 21h 18m 27.18622s[1] |
Declination | +43° 56′ 45.3992″[1] |
Apparent magnitude (V) | 5.00[2] |
Characteristics | |
Spectral type | O7.5IIIn((f))[3][4] |
U−B color index | −0.94[2] |
B−V color index | −0.01[2] |
Variable type | ELL[5][n 1] |
Astrometry | |
Radial velocity (Rv) | 1 ± 5[6] km/s |
Proper motion (μ) | RA: +4.632[1] mas/yr Dec.: −8.487[1] mas/yr |
Parallax (π) | 1.4498 ± 0.1152 mas[1] |
Distance | 2,200 ± 200 ly (690 ± 50 pc) |
Absolute magnitude (MV) | −7.9[7] |
Details | |
Mass | 23[8] M☉ |
Surface gravity (log g) | 3.6[9] cgs |
Temperature | 34,000[9] K |
Rotational velocity (v sin i) | 399[4] km/s |
Other designations | |
Database references | |
SIMBAD | data |
68 Cygni is currently classified as a rotating ellipsoidal variable, varying between apparent magnitudes 4.98 and 5.09, although the classification as a rotating ellipsoidal variable is subject to controversy. Barely visible to the naked eye, the star is likely to have a mass of around 26 solar masses and a temperature of approximately 34,000 kelvins, although many of the star's physical parameters are subject to uncertainties due to the unclear nature of the system.