How Star Formation Modes and Thresholds manifest in Molecular Cloud Structure
T. Pillai (Caltech), R. Shetty (ZfA Heidelberg), G. Parmentier (University Bonn), K. Tassis (JPL), Philip C. Myers (CfA), Alyssa A. Goodman (CfA)
We discuss how molecular cloud structure on spatial scales of <0.1 pc to ~10 pc influences the type of stars formed by a given cloud (Kauffmann et al. 2010a,b, ApJ). Massive star formation (MSF), e.g., only occurs in cloud fragments of mass >870 M¤ (r/pc)1.33, where r is the fragment radius (Kauffmann & Pillai 2010c, ApJL). This research provides a unique and critical tool to research the star formation modes and thresholds discussed during this meeting. In contrast to traditional research on thresholds, the spatial scale of measurements is explicitly taken into account. New Herschel data refine our laws (Kauffmann et al., in prep). Initial models of MSF in clusters (Parmentier et al. 2011, MNRAS), and of MSF in collapsing dense cores (Tassis & Kauffmann, in prep.), provide interesting quantitative matches to the above MSF limit. We show in examples how his approach permits to directly compare nearby (<500 pc), distant (~4000 pc), and extragalactic clouds (few Mpc, with ALMA).