A DEEP UBVRI CCD PHOTOMETRY OF SIX OPEN STAR CLUSTERS IN THE GALACTICANTICENTER REGION

摘要

We present deep UBVRI CCD photometry of six open star clusters situated in the Galactic anticenter region(l ~ 120-200°). The sample includes three unstudied (Be 6, Be 77, King 17) and three partly studied open clusters(Be 9, NGC 2186, and NGC 2304). The fundamental parameters have been determined by comparing color—colorand color—magnitude diagrams with the theoretical models. The structural parameters and morphology of theclusters were discussed on the basis of radial density profiles and isodensity contours, respectively. The isodensitycontours show that all the clusters have asymmetric shapes. An investigation of structural parameters indicates thatthe evolution of core and corona of the clusters is mainly controlled by internal relaxation processes.