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Project Progress

The goal of this task is to determine the chemical composition of icy bodies and establish their potential for delivering pre-biotic organic materials and water to the young Earth and other planets. This is being performed through detailed chemical modeling, coupled with physical evolution, of the protosolar nebula. Related observational, theoretical, and laboratory subprojects are also being undertaken.

Two book review chapters have been published on interstellar and nebular chemistry have just been published (Nuth et al. 2006; Ciesla & Charnley 2006). Along with colleagues at the James Clerk Maxwell Telescope (JCMT), we participated in the world-wide observing campaign for the Deep Impact experiment (Meech et al. 2005)

Observations aimed at delineating possible interstellar and nebular chemistries contributions to cometary composition have been made. We have detected interstellar heavy water for the first time using JCMT. The 110-101 transition at 316.7 GHz was detected in absorption towards a deeply-embedded protostar; the derived abundance and D/H ratio are consistent with an origin in cold gas phase chemistry, with the observed molecules having been subsequently frozen out as ice (Butner et al. 2006, in preparation). Additionally, and in response to a critique of our earlier work, we have observed several more lines of interstellar glycine using telescopes at the Arizona radio Observatory. We have also recently made a further attempt to detect the DNA base analog Pyrimidine with the Submillimeter Array. Building on our previous SMA mapping of organic molecules in low-mass `hot corinos’, VLA observations of HCOOCH₃ have been undertaken with NAI collaborators L. Mundy and J. Pedelty. Data from these three projects is presently being reduced.

To account for our discovery of very high D/H ratios in cometary formaldehyde, we made more studies of gas-grain deuterium fractionation processes in the comet-forming regions of model disks. A significant amount theoretical effort has been expended on developing a new disk chemistry model. The aim in this work is to treat the coupling between dynamics and chemistry in a novel manner that is markedly different from existing codes. This work is ongoing should represent a major advance in modeling these complex processes in a reliable and efficient manner.