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H-alpha RGB amateur image of ξ Cygni, center star, at edge of NGC7000
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NGC 7000 (North America Nebula). ξ Cygni is the bright star on the left.
ξ Cygni (Latinised as Xi Cygni) is a spectroscopic binary star in the constellation Cygnus. Its apparent magnitude is 3.73 and it is located around 360 parsecs (1,200 ly) away.
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Cygnus |
Right ascension | 21h 04m 55.874s[1] |
Declination | +43° 55′ 40.285″[1] |
Apparent magnitude (V) | 3.73[2] |
Characteristics | |
Spectral type | K4:Ib- + A1.5V[3] |
U−B color index | +1.78[2] |
B−V color index | +1.66[2] |
Astrometry | |
Radial velocity (Rv) | -19.10[4] km/s |
Proper motion (μ) | RA: +9.763[5] mas/yr Dec.: +0.646[5] mas/yr |
Parallax (π) | 3.59 ± 0.45 mas[5] |
Distance | approx. 900 ly (approx. 280 pc) |
Absolute magnitude (MV) | −4.3/+1.3[3] |
Orbit[6] | |
Period (P) | 6,750 ± 200 days |
Semi-major axis (a) | ~766 R☉ |
Eccentricity (e) | 0.25 ± 0.07 |
Inclination (i) | ~50° |
Details | |
Primary | |
Mass | ~8[6] M☉ |
Radius | 174[1] R☉ |
Luminosity | 6,081 - 6,368[1] L☉ |
Surface gravity (log g) | 1.00[7] cgs |
Temperature | 3,898±170[1] K |
Metallicity [Fe/H] | −0.41[7] dex |
Secondary | |
Mass | ~2.5[6] M☉ |
Other designations | |
Database references | |
SIMBAD | data |
The system contains two stars which orbit every 18 years in a mildly eccentric orbit. The primary star is a supergiant with a spectral type of around K4, while the secondary is an A-type main-sequence star with a spectral type of A1.5. Stellar winds from the supergiant have been measured at around 50 km/s, but with variations in speed and individual line strengths.[6]
ξ Cygni is in the Kepler spacecraft's field of view but no planets have been detected.[8]