Open cluster in the constellation Cygnus
NGC 6866 is a young open cluster of stars in the northern constellation Cygnus. It was discovered by German astronomer Caroline Herschel on 23 July 1783. This cluster is located at an estimated distance of from the Sun, and is circling the galactic center with a slight orbital eccentricity of 0.12. It shows a heliocentric radial velocity of .
The angular radius of the cluster is estimated as about , while the core radius is . A total of 1,357 main sequence stars are determined to be likely cluster members. The combined mass of member stars is estimated as . It shows a loss rate of 1.92 stars per million years. The metallicity of the cluster – the abundance of elements of greater mass than helium – is similar to that in the Sun.
NGC 6866 is one of four clusters located in what was the field of view of the Kepler space telescope. Using asteroseismic analysis of the Kepler data, the age of NGC 6866 is estimated to be about 430 million years old. The cluster includes 31 Delta Scuti and 8 Gamma Doradus variables, with four eclipsing binaries, and 106 stars displaying rotational modulation that is indicative of star spots. Two systems are W Ursae Majoris variables.
References.
 ;templatestyles src="Reflist/styles.css" / ;
External links.
 ;indicator name="01-sky-coordinates" ; ;templatestyles src="Template:Sky/styles.css" / ;Coordinates: &amp;de=44.0&amp;zoom=&amp;show_grid=1&amp;show_constellation_lines=1&amp;show_constellation_boundaries=1&amp;show_const_names=1&amp;show_galaxies=1&amp;img_source=IMG_all 20h 03m 42s, +44° 00′ 00″ ;/indicator ;