9 Cygni

9 Cygni
Observation data; Equinox J2000.0]] (ICRS)
Constellation	Cygnus
Right ascension	19h 34m 50.9285s
Declination	+29° 27′ 46.697″
Apparent magnitude (V)	5.39 (5.9 + 6.4)
Characteristics
Evolutionary stage	Red clump + main sequence
Spectral type	G8 IIIa + A2 V
B−V color index	0.581
Astrometry
Radial velocity (Rv)	20.09±1.98 km/s
Proper motion (μ)	RA: +14.822 mas/yr ; Dec.: +13.554 mas/yr
Parallax (π)	5.4904 ± 0.0892 mas
Distance	594 ± 10 ly ; (182 ± 3 pc)
Absolute magnitude (MV)	−0.70
Orbit
Period (P)	4.56 yr
Semi-major axis (a)	0.030″
Eccentricity (e)	0.82
Inclination (i)	114.6°
Longitude of the node (Ω)	29.3°
Periastron epoch (T)	1985.56
Argument of periastron (ω); (secondary)	45.5°
Details
9 Cyg A
Mass	2.9±0.4 M☉
Radius	18.2 R☉
Surface gravity (log g)	3.040±0.370 cgs
Temperature	5,047 K
Metallicity [Fe/H]	−0.260±0.090 dex
9 Cyg B
Mass	2.7±0.4 M☉
Radius	3.5 R☉
Temperature	9,247 K
Age	437.1 Myr
Other designations
	BD+29 3651, HIP 96302, HR 7441, SAO 87385
	9 Cyg A: {{{names1}}}
	9 Cyg B: {{{names2}}}
Database references
SIMBAD	data

Short description: Star in the constellation Cygnus

9 Cygni is a binary star system in the northern constellation of Cygnus. 9 Cygni is its Flamsteed designation. The two stars have a combined magnitude of 5.39,^[2] so it can be seen with the naked eye under good viewing conditions. Parallax measurements made by Gaia put the star at a distance of around 590 light-years (182 parsecs) away.^[1]

The two stars of 9 Cygni are a G-type giant and an A-type star. Both stars are over twice as massive as the Sun.^[2] They orbit once every 4.56 years, separated with a semi-major axis of 0.030 arcseconds. However, the eccentricity is high, at 0.82.^[3] The primary is a red clump giant, a star on the cool end of the horizontal branch fusing helium in its core. The secondary star has begun to evolve off the main sequence; it is sometimes classified as a giant star^[2] and sometimes as a main-sequence star.^[4]

References

↑ ^1.0 ^1.1 ^1.2 ^1.3 ^1.4 ^1.5 ^1.6 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G.
↑ ^2.0 ^2.1 ^2.2 ^2.3 ^2.4 ^2.5 ^2.6 ^2.7 Ginestet, N.; Carquillat, J. M. (2002). "Spectral Classification of the Hot Components of a Large Sample of Stars with Composite Spectra, and Implication for the Absolute Magnitudes of the Cool Supergiant Components". The Astrophysical Journal Supplement Series 143 (2): 513–537. doi:10.1086/342942. Bibcode: 2002ApJS..143..513G.
↑ ^3.0 ^3.1 ^3.2 "Sixth Catalog of Orbits of Visual Binary Stars". United States Naval Observatory. http://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/wds/orb6.
↑ ^4.0 ^4.1 ^4.2 ^4.3 ^4.4 ^4.5 ^4.6 ^4.7 Eggleton, Peter P.; Yakut, Kadri (2017). "Models for 60 double-lined binaries containing giants". Monthly Notices of the Royal Astronomical Society 468 (3): 3533. doi:10.1093/mnras/stx598. Bibcode: 2017MNRAS.468.3533E.
↑ ^5.0 ^5.1 Soubiran, Caroline; Le Campion, Jean-François; Brouillet, Nathalie; Chemin, Laurent (2016). "The PASTEL catalogue: 2016 version". Astronomy & Astrophysics 591: A118. doi:10.1051/0004-6361/201628497. Bibcode: 2016A&A...591A.118S.
↑ "* 9 Cyg". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=%2A+9+Cyg.

Observation data Equinox J2000.0]] (ICRS)
Constellation	Cygnus
Right ascension	19^h 34^m 50.9285^s^[1]
Declination	+29° 27′ 46.697″^[1]
Apparent magnitude (V)	5.39^[2] (5.9 + 6.4)^[3]
Characteristics
Evolutionary stage	Red clump + main sequence^[4]
Spectral type	G8 IIIa + A2 V^[4]
B−V color index	0.581^[2]
Astrometry

Radial velocity (R_v)	20.09±1.98^[1] km/s
Proper motion (μ)	RA: +14.822^[1] mas/yr Dec.: +13.554^[1] mas/yr
Parallax (π)	5.4904 ± 0.0892^[1] mas
Distance	594 ± 10 ly (182 ± 3 pc)
Absolute magnitude (M_V)	−0.70^[2]

Orbit^[3]
Period (P)	4.56 yr
Semi-major axis (a)	0.030″
Eccentricity (e)	0.82
Inclination (i)	114.6°
Longitude of the node (Ω)	29.3°
Periastron epoch (T)	1985.56
Argument of periastron (ω) (secondary)	45.5°
Details
9 Cyg A
Mass	2.9±0.4^[2] `M`_☉
Radius	18.2^[4] `R`_☉
Surface gravity (log g)	3.040±0.370^[5] cgs
Temperature	5,047^[4] K
Metallicity [Fe/H]	−0.260±0.090^[5] dex
9 Cyg B
Mass	2.7±0.4^[2] `M`_☉
Radius	3.5^[4] `R`_☉
Temperature	9,247^[4] K
Age	437.1^[4] Myr
Other designations
BD+29 3651, HIP 96302, HR 7441, SAO 87385^[6]
9 Cyg A: {{{names1}}}
9 Cyg B: {{{names2}}}
Database references
SIMBAD	data

9 Cygni

Topic: Astronomy

References

See also