17 Cygni

17 Cygni is the Flamsteed designation for a multiple star system^[5] in the northern constellation of Cygnus. It has an apparent visual magnitude of 5.00,^[2] so, according to the Bortle scale, it is visible from suburban skies at night. Measurements of the annual parallax find a shift of 0.0477″,^[1] which is equivalent to a distance of around 68.5 ly (21.0 pc) from the Sun. It has a relatively high proper motion, traversing the celestial sphere at the rate of 0.451″/year.^[14]

Apparentmagnitude(V)5.00^[2]

Apparentmagnitude(V)8.55^[4]

SpectraltypeF7 V^[2] + K6 V + K3 V + K3 V^[5]

B−V color index0.46^[2]

Quick facts Observation data Epoch J2000 Equinox J2000, Apparent magnitude (V) ...

17 Cygni

Location of 17 Cygni (circled in red)
Observation data Epoch J2000      Equinox J2000
Constellation	Cygnus
A
Right ascension	19h 46m 25.600s[1]
Declination	+33° 43′ 39.35″[1]
Apparent magnitude (V)	5.00[2]
B
Right ascension	19h 46m 27.547s[3]
Declination	+33° 43′ 48.89″[3]
Apparent magnitude (V)	8.55[4]
Characteristics
Spectral type	F7 V[2] + K6 V + K3 V + K3 V[5]
B−V color index	0.46[2]
Astrometry
A
Radial velocity (Rv)	+4.1[6] km/s
Proper motion (μ)	RA: +22.745 mas/yr[1] Dec.: –448.311 mas/yr[1]
Parallax (π)	47.6516±0.0675 mas[1]
Distance	68.45 ± 0.10 ly (20.99 ± 0.03 pc)
Absolute magnitude (MV)	+3.34[7]
B
Radial velocity (Rv)	+3.7[6] km/s
Proper motion (μ)	RA: +21.547 mas/yr[3] Dec.: –438.730 mas/yr[3]
Parallax (π)	47.7379±0.0185 mas[3]
Distance	68.32 ± 0.03 ly (20.948 ± 0.008 pc)
Absolute magnitude (MV)	+6.91[7]
Details
A
Mass	1.24[8] M☉
Radius	1.538[9] R☉
Luminosity	3.66[10] L☉
Surface gravity (log g)	4.262[10] cgs
Temperature	6,455[10] K
Metallicity [Fe/H]	0.027[10] dex
Rotational velocity (v sin i)	9[2] km/s
Age	2.8[7] Gyr
B
Mass	0.78[11] M☉
Radius	0.70[11] R☉
Luminosity	0.21[11] L☉
Surface gravity (log g)	4.62[11] cgs
Temperature	4,652[11] K
F
Mass	0.77[11] M☉
Radius	0.71[11] R☉
Luminosity	0.24[11] L☉
Surface gravity (log g)	4.62[11] cgs
Temperature	4,789[11] K
Rotational velocity (v sin i)	3.6[12] km/s
G
Mass	0.75[11] M☉
Radius	0.71[11] R☉
Luminosity	0.22[11] L☉
Surface gravity (log g)	4.61[11] cgs
Temperature	4,686[11] K
Rotational velocity (v sin i)	3.0[12] km/s
Other designations
17 Cyg, BD+33°3587, GJ 767.1, GJ 9670, HD 187013, HIP 97295, HR 7534, SAO 68827[13]
Database references
SIMBAD	data
	B
	F
	G

Close

This system consists of two visual binary systems that were discovered by John Herschel in the 1820s. Components A and B form a bright, wide pair with an angular separation of 26.0 arcsecond and an estimated orbital period of ~6,200 years. The faint, close system consists of components F and G with a separation of 2.6 arcsecond and a period of 238 years. The two binaries form a hierarchical system with a separation of about 800 arcseconds and orbital period of 3.7 million years or more.^[5] Although the CCDM lists four other companions, these are not associated with the system.^[15]

The stellar classification of the primary star, component A, is F7 V,^[2] which means it is a main sequence star like the Sun. The star has 1.24^[8] times the mass of the Sun and 1.54^[9] times the Sun's radius. It is some 2.8^[7] billion years old and shines with 3.66^[10] times the Sun's luminosity. The effective temperature of the stellar atmosphere is 6,455^[10] K, giving it the yellow-white hued glow of an F-type star.^[16]