Column density probability distributions as probes of atomic and molecular gas in the star-forming ISM. Jouni Kainulainen Max-Planck-Institute for Astronomy, Heidelberg, Germany
Gravitationally bound dense cores are the most direct precursors of stars we currently know. However, the mechanisms regulating their formation are not well constrained. Indeed, the description of structure formation in molecular clouds is an essential, yet missing element in building global laws of star formation. In analytical models of star formation, the probability distribution function (PDF) of volume densities in molecular clouds has a profound impact on the structure formation inside them. In this contribution, we discuss the impact of recent observational studies regarding column density PDFs to understanding structure formation in molecular clouds and to the stability of cloud structures. In particular, we discuss about the possibilities to use the observed dust column density PDFs to gain information on low-column density, (partly) atomic envelopes surrounding molecular clouds. Finally, we describe our efforts to build extremely-high dynamic range PDFs and the advantages offered by such data.
Collaborators: H. Beuther, MPIA, Germany T. Henning, MPIA, Germany	Key publication