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Interstellar Precursors of Meteoritic Organics - A Theoretical Study
PI: Steven Charnley
It is proposed to continue theoretical studies of organic astrochemistry. The principal goals of this project are to identify interstellar molecules in the soluble organic extracts of carbonaceous meteorites, and to quantify the viability of the many interstellar organics which have been proposed as precursors of more complex meteoritic molecules formed by aqueous alteration chemistry. This will be done by chemical kinetic modeling of gas and solid phase processes, as constrained by comparison with the complex molecular inventory of meteorites and molecular clouds.
Stochastic simulations will be performed to investigate pathways to molecular complexity through cold atom addition reactions on the surfaces of dust grains. The expected isotopic fractionation patterns (e.g. in D and $\rm ^{13}C$) for the putative interstellar precursor molecules required by processes such as the Strecker synthesis will be computed and compared to the meteoritic data. The interstellar production of amino acids, in gas phase syntheses driven by ice evaporation in warm protostellar environments, will be evaluated. The isototopic fractionation patterns in large interstellar organic compounds as a function of synthesis route will also be calculated and compared to recent meteoritic analyses. The modeling effort will employ experimental data on surface processes and ion-molecule reactions provided by our collaborators. It is also proposed to undertake a modest observing program to search for new organics predicted by our theoretical work.
The proposed research meshes with NASA’s strategic goals, and those of the Exobiology and Evolutionary Biology Program. The results of this study will allow us to quantify the relative contribution, direct or indirect, of various interstellar chemical processes to specific classes of meteoritic organics. This will enable us to assess their general relevance for providing materials capable of initiating prebiotic chemistry in planetary systems.
May 16, 2012
