Maximum stellar mass versus cluster membership number revisited

Abstract

ABSTRACT We have made a new compilation of observations of maximum stellar mass versus cluster membership number from the literature, which we analyse for consistency with the predictions of a simple random drawing hypothesis for stellar mass selection in clusters. Previously, Weidner and Kroupa have suggested that the maximum stellar mass is lower, in low-mass clusters, than would be expected on the basis of random drawing, and have pointed out that this could have important implications for steepening the integrated galactic initial mass function (IGIMF) at high masses. Our compilation demonstrates how the observed distribution in the plane of maximum stellar mass versus membership number is affected by the method of target selection; in particular, rather low n clusters with large maximum stellar masses are abundant in observational data sets that specifically seek clusters in the environs of high-mass stars. Although we do not consider our compilation to be either complete or unbiased, we discuss the method by which such data should be statistically analysed. Our very provisional conclusion is that the data are not indicating any striking deviation from the expectations of random drawing. © 2008 RAS.