Η_Cygni
Eta Cygni
Star in the constellation Cygnus
Eta Cygni (η Cygni) is a star in the northern constellation of Cygnus. It is visible to the naked eye with an apparent visual magnitude of 3.889.[2] The star lies along the main body of the constellation, about midway between Gamma Cygni and Albireo.[8] Based upon an annual parallax shift of 24.17 mas,[1] it is located 135 light years from the Sun.
At an age of about 3.3[6] billion years, this is an evolved red clump[9] giant star with a stellar classification of K0 III.[3] It is presently on the horizontal branch and is generating energy through the nuclear fusion of helium at its core. The star has about 1.59[6] times the mass of the Sun and has expanded to 11[4] It radiates 52.5 times the solar luminosity from its outer atmosphere at an effective temperature of 4,783 K.[6]
Eta Cygni has five visual companions,[10] of which only component B appears to be physically associated. This magnitude 12.0 star lies at an angular separation of 7.80 arc seconds along a position angle of 206°, as of 2007.[11]