Young Open Clusters as Probes of the Star-Formation Process. II. Mass and Luminosity Functions of Young Open Clusters

This paper is the second in a series devoted to the use of young, optically revealed open clusters as probes of the star-formation process. The first paper in the series presented the dataset used for the study, and discussed some of the results from the survey of 23 open clusters in the Cassiopeia region of the Perseus spiral arm of our Galaxy. This paper presents an analysis of the stellar content of a subset of the clusters, including determinations of the luminosity and mass functions of 8 of the clusters to approximately 1 solar mass. The slope of the average mass function Gamma is found to be -1.40 +/- 0.13 over the mass range 1.4 less than M/solar mass less than 7.9. Significant variations from this average value are found for two of the clusters, NGC 581 and NGC 663. Possible structure in the mass functions is discussed, as is the degree to which the initial mass function (IMF) is universal, or merely an average of many IMFs that differ substantially on the local level.