Research Training Network - FP6

Scientific quality of the proposal

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Scientific originality of the project

Over the last 20 years, some 150 molecules have been detected in interstellar space. These range from simple diatomics such as molecular hydrogen and carbon monoxide to very complex species such as large carbon chains containing up to 11 carbon atoms and Polycyclic Aromatic Hydrocarbon molecules with typically 50 C-atoms. In the coming decade, the new European/US observatories coming on line will increase this inventory of the molecular universe by orders of magnitude. Identification of the detected lines with specific molecular species, their analysis in terms of the physical conditions in the regions, and the implications of these data for the phyiscal and chemical processes ruling the universe require a close synergy between laboratory spectroscopists, molecular physicists, chemists, and astronomers. This requires a new and innovative approach to this field and that is precisely the scope of this network. This network will, for the first time, enlist scientists in all of these areas to work together towards this common goal: Charting the molecular universe. The identification of specific species in space requires direct comparison of the particular frequencies of emission or absorption lines observed in interstellar space with spectroscopic measurements of known species in a controlled laboratory experiment. In order to interpret the measured laboratory spectra in terms of the properties of the molecule (ie., assign lines to specific transitions), supporting molecular physics quantum chemical calculations are required. The intensities of lines observed in space depend directly on the collisional excitation rates of the molecules with the predominant collision partners, atomic or molecular hydrogen and helium. These rates will have to be calculated using quantum chemical methods or measured in the laboratory by molecular physicists. Such rates can then be used by astronomers to determine the physical conditions and the abundances of the molecules involved in the interstellar regions where the emission or absorption arises. The abundances of interstellar molecules are the result of a balance between formation and destruction reactions. The rate coefficients and products of relevant reactions will have to be measured under astrophysically relevant conditions (eg., low temperature, low pressure) or quantum chemically calculated. These rates can then be used by astronomical modelers to calculate the abundances of interstellar species. For example, when specific reaction routes have been proposed and the relevant reaction rate coefficients measured, abundances of new species can be predicted. Laboratory spectroscopists can then measure their transition frequencies while molecular physicists can calculate their excitation rate coefficients. All of these data together can then be used by astronomical modelers to predict the expected line intensities of new species which can then be targeted in specific searches. It is clear that action in all of these four science areas has to be strongly interwoven in studies of the molecular universe. In our workplan, we have identified 6 key topics in the areas of molecular complexity in space and in chemistry of regions of star formation: Water in the universe, carbon chemistry, deuterium: coming in from the cold, ionization along the star formation trail, nitrogen chemistry as tracers of protostellar condensations, and molecular tracers of shocks. In each of these topics, we expect that our highly interdisciplinary network can make major breakthroughs thanks to its unique collaborative framework.