The BHK color diagram: A tool to study young stellar populations

A new method to derive age differences between the various super-star-clust ers observed in starburst galaxies using the two-color diagram B-H versus H -K is presented. This method offers a quick and easy way to differentiate v ery young and intermediate-age stellar populations even if data on extincti on are unavailable. In this case, discrimination of regions younger and old er than 4 Myr is feasible. With the availability of data on extinction, the time resolution can be improved significantly. The application of the meth od to the starbursting system Arp 299 is presented. The validity of the met hod is confirmed by comparing the equivalent width of the H alpha line with the chronological map of the northern part of NGC 3690.