A NEW METHOD TO DETERMINE STAR-FORMATION HISTORIES OF NEARBY GALAXIES

A new method for the study of the star formation histories of nearby g alaxies with resolved stars is presented here. Rather than adopting tr aditional methods of creating synthetic color-magnitude diagrams (CMDs ) with various star formation histories, the approach taken is to crea te a set of CMDs which can be combined linearly to reproduce almost an y star formation history, and use a numerical fit to solve the problem . In addition, a quantitative fit parameter for determining the simila rity of an observed and a theoretical CMD is presented, along with a n umber of tests of this parameter. Finally, a rigorous test of the meth od is given. (C) 1997 Elsevier Science B.V.