9 Cygni
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, 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 () away.

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. They orbit once every 4.56 years, separated with a semi-major axis of . However, the eccentricity is high, at 0.82. 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 and sometimes as a main-sequence star.
Q50053
binary star
Concept
Q8928
constellation
Concept
Q8921
Cygnus
CEL
Q111116
Flamsteed designation
Concept
Q906561
Parallax
Concept
Q767805
Gaia
MISC
Q5875
giant
Concept
Q25377588
A-type star
Concept
Q525
Sun
CEL
Q21143897
semi-major axis
UNK
Q208474
eccentricity
Concept
Q1358411
red clump
Concept
Q50076
horizontal branch
Concept
Q3450
main sequence
Concept
Q3450
main-sequence star
Concept
Q10940891
9 Cygni
Concept
Q10940891
9 Cygni
Concept
Q10940891
9 Cygni
Concept
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9
NUMBER
+9^^http://www.w3.org/2001/XMLSchema#decimal
9
NUMBER
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NUMBER
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NUMBER
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NUMBER
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0.82
NUMBER
constellation
instance of