Messier 39

This cluster has an estimated mass of 232 M_☉ and a linear tidal radius of 8.6±1.8 pc. Of the 15 brightest components, six form binary star systems; one more is suspected. HD 205117 is a probable eclipsing binary system with a period of 113.2 days that varies by 0.051 in visual magnitude. Both members seem to be subgiants. Within are at least five chemically peculiar stars and ten suspected short-period variable stars.

Map