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Universität zu Köln
Mathematisch-Naturwissenschaftliche Fakultät

I. Physikalisches Institut

Sonderforschungsbereich 494

Project Section B4

The chemical complexity of molecular clouds

This project is a continuation of project B4 of the last Collaborative Research Center (CRC) funding period. It builds on results obtained there, but focuses on and extends a number of topics which have emerged as the most interesting to pursue. The project seeks to map the limits of chemical complexity of interstellar molecular clouds in more than one sense – in the spatial and in the frequency dimensions. What is the large-scale organic content of molecular clouds? Is it possible to discover ever more complex species? What are the limits of the observability of complex molecules in dense, hot protostellar environments? How common are hot cores with a rich chemistry? To address the first two questions, we propose observations of molecular clouds around the Galactic center. We argue that these clouds’ extreme environment makes chemical properties visible that remain hidden in ordinary clouds. To that end we propose extensive mapping of the central molecular zone in the methanol molecule. Together with our understanding of methanol excitation we shall be able to analyse densities and temperatures and with observations of more complex species illuminate these regions’ chemical richness. Highly successful unbiased line survey projects recently started by us have led to amazing databases that require substantial follow-up to exploit their full potential. In particular, two very high luminosity protostellar sources near the Galactic center are found to show thousands of lines in the 3 mm range, with certainly many from not yet reported species amongst them. We argue that (sub)mm interferometry is needed for conclusive identification as well as for the meaningful determination of excitation conditions. Our survey provides a fantastic starting point for such efforts. Furthermore, we argue that there may be a fundamental high frequency limit above which it is fundamentally impossible to study molecules in the densest and hottest regions around protostars, which would seriously compromise planned ground-, airplane- and satellite-based THz line surveys of these object. Paragraph of our proposal describes attempts to probe that limit, and to discover which objects are affected.


See the MPIfR home page for more information.