Eta Cygni
Star in the constellation Cygnus / From Wikipedia, the free encyclopedia
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.
Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
---|---|
Constellation | Cygnus |
Right ascension | 19h 56m 18.37222s[1] |
Declination | +35° 05′ 00.3228″[1] |
Apparent magnitude (V) | 3.889[2] |
Characteristics | |
Spectral type | K0 III[3] |
U−B color index | +0.881[2] |
B−V color index | +1.035[2] |
Astrometry | |
Radial velocity (Rv) | −25.87±0.14[4] km/s |
Proper motion (μ) | RA: −33.61[1] mas/yr Dec.: −27.87[1] mas/yr |
Parallax (π) | 24.17 ± 0.15 mas[1] |
Distance | 134.9 ± 0.8 ly (41.4 ± 0.3 pc) |
Absolute magnitude (MV) | 0.74[5] |
Details[4] | |
Mass | 1.59[6] M☉ |
Radius | 11 R☉ |
Luminosity | 52.5 L☉ |
Surface gravity (log g) | 2.7 cgs |
Temperature | 4,783±20[6] K |
Metallicity [Fe/H] | −0.09 dex |
Rotational velocity (v sin i) | 2.2 km/s |
Age | 3.29[6] Gyr |
Other designations | |
Database references | |
SIMBAD | data |
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]