Xi Cygni

ξ Cygni (Latinised as Xi Cygni) is a spectroscopic binary star in the constellation Cygnus, made up of a K-type supergiant star (primary) and an A-type star (secondary). Its apparent magnitude is 3.73, making it readily visible to the naked eye, and it is located around 350 parsecs (1,100 ly) away.

ξ Cygni

Location of ξ Cygni (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Cygnus
Right ascension	21h 04m 55.8599s[1]
Declination	+43° 55′ 40.272″[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: +10.062[1] mas/yr Dec.: +0.861[1] mas/yr
Parallax (π)	2.8363±0.1269 mas[1]
Distance	1,150 ± 50 ly (350 ± 20 pc)[1]
Absolute magnitude (MV)	−4.3/+1.3[3]
Orbit[5]
Period (P)	6,750 ± 200 days
Semi-major axis (a)	~766 R☉
Eccentricity (e)	0.25 ± 0.07
Inclination (i)	~50°
Details[6]
Primary
Mass	~8[5] M☉
Radius	220.09+9.64 −10.56 R☉
Luminosity	9889±964 L☉
Surface gravity (log g)	0.89 cgs
Temperature	3,878±33 – 4,031 K
Metallicity [Fe/H]	−0.26 dex
Secondary
Mass	~2.5[5] M☉
Other designations
62 Cygni, FK5 792, GC 29459, HIP 104060, HR 8079, HD 200905, SAO 50424
Database references
SIMBAD	data

Characteristics

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.^[5]

The distance to Xi Cygni is of about 350 parsecs (1,100 ly), based on parallax measurements.^[1] At this distance, the apparent magnitude is diminished by 0.16 magnitudes.^[6]

ξ Cygni is in the Kepler spacecraft's field of view but no planets have been detected.^[7]

Gallery

• 
  H-alpha RGB amateur image of ξ Cygni, center star, at edge of NGC7000
• 
  NGC 7000 (North America Nebula). ξ Cygni is the bright star on the left.