The Stellar Initial Mass Function: Constraints from Young Clusters and Theoretical Perspectives

摘要

We summarize recent observational and theoretical progress aimed atunderstanding the origin of the stellar initial mass function (IMF) withspecific focus on galactic star-forming regions. We synthesize data fromvarious efforts to determine the IMF in very young, partially-embedded stellarclusters and find: i) no significant variations in the low-mass IMF have beenobserved between different star-forming regions; and ii) the mass distributionsof young stars just emerging from molecular clouds are consistent with havingbeen drawn from the IMF derived from field stars in the solar neighborhood.These results apply only to gross characterizations of the IMF (e.g. the ratioof high to low mass stars); present observations do not rule out more subtleregional differences. Further studies are required in order to assess whetheror not there is evidence for a universal turnover near the hydrogen--burninglimit. We also provide a general framework for discussing theories of the IMF,and summarize recent work on several physical mechanisms which could play arole in determining the form of the stellar initial mass function.