EPoS Contribution
EPoS Contribution
The Massive Star Formation Limit in the Mass-Size Space of Molecular Structures

Genevieve Parmentier
Max-Planck-Institut fuer Radioastronomie, Bonn, Germany
In this contribution I present an interpretation of the massive star formation (MSF) limit in the mass-size space of molecular structures highlighted by Kauffmann & Pillai (2010), that is, m(r)=870(r/pc)^1.3 M_o. It is shown that for sensible choices of molecular clump density index (e.g. density profile slope of about -1.7), the clumps obeying the MSF limit all have the same mass of gas denser than a given volume density threshold. Specifically, the MSF limit describes clumps containing 150M_o of gas denser than a number density threshold of n_th=10^4cm^-3. Assuming the canonical star formation efficiency of 0.30 then yields an embedded-cluster mass of 50M_o, namely, the lower mass limit of a cluster for its initial stellar mass function to be populated up to 10M_o. Under the hypothesis of a volume density threshold for star formation of n_th=10^4cm^-3, the observationally inferred MSF limit therefore equates with a threshold in star-forming gas mass beyond which the star-forming gas reservoir is large enough to allow the formation of massive stars. A similar line of reasoning can be applied to the formation of single massive stars based on a number density threshold of n_th=10^5cm^-3.
Caption: Mass-size space of molecular structures. Symbols: molecular clumps selected for their massive star formation activity. Lines: models of the massive star formation limit (red: for single massive stars -- blue: for embedded clusters)
J. Kauffmann, JPL, USA
T. Pillai, Caltech, USA
K. M. Menten, MPIfR, Germany
Key publication