2007/11/30 by G. Maciejewski, Maciejewski, G., Ts. Georgiev +3
Physics and Astronomy · #Astrophysics (astro-ph) #FOS: Physical sciences #astro-ph
paper · pdf · doi:10.48550/arxiv.0711.4916
9 pages, 3 figures, accepted for publication in AN
arxiv created 2007/11/30 · arxiv updated 2009/12/01
The results of CCD photometric survey performed with the 90/180 cm Schmidt-Cassegrain Telescope of the Nicolaus Copernicus University Astronomical Observatory in Piwnice (Poland) and the 70/172 cm Schmidt Telescope of the National Astronomical Observatory (NAO) at Rozhen (Bulgaria) of the field of 1 Gyr old open cluster NGC 6939 are presented. Twenty two variable stars were detected, four of them previously known. Four eclipsing systems (3 detached and 1 contact binary) were found to be members of the cluster. Analysis of the brightness of the contact binary V20 strongly supports the distance to the cluster of 1.74 +/- 0.20 kpc. The small population of contact binaries in NGC 6939 confirms also the relatively young age of the cluster.