NASA Astrobiology Institute (NAI)

Interstellar ices show a varied composition with distinct water-rich and inert components consisting of a variety carbon-bearing species. Hydrogenation and oxidation reactions are equally important on the grain surface and drive most of the chemistry that occurs. Reactions involving carbon monoxide on the grain surface are known to be the dominant chemical pathways to many organic species like methanol and formaldehyde. Astronomical observations suggest that the larger organic species like ethanol and acetaldehyde are linked through successive hydrogenation of CO. However, the formation pathways (on the grain surface) of larger molecules like acetaldehyde and ethanol which form via formaldehyde and the efficiency of these pathways have not been determined. This aim of this project is model the pertinent grain surface reaction in order to assess the effectiveness of CO hydrogenation as the main pathway to more complex organic species.

The project is in the initial stages of researching the various chemical pathways (for molecules such as acetaldehyde and ethanol) which we wish to model as well as the parameter space (i.e. activation barriers, temperature dependence, products) that must be explored. A number of sub-millimeter studies of hot molecular cores have already been conducted and we will use these literature values, of for example ethanol, acetaldehyde, and formamide, in order to test our reaction schemes.