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Ronald Snell

Research Interests: Molecular Cloud Chemistry

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The complex chemistry of the molecular interstellar medium presents a significant challenge to astrophysicists. Observationally, the estimation of molecular abundances is difficult because the accuracy of the estimate is often limited by knowledge of the physical conditions within the cloud. For that reason, we have been undertaking a number of extensive studies of both dark cloud and GMC cloud cores where we have obtained a comprehensive data sets that permit derivation of both physical and chemical properties. Such studies are made possible with the sensitive array receivers at the FCRAO. Variations in the abundance of key molecular species have been found in several cloud cores and suggest variations in the chemical age. One of our goals is to use this measure of the chemical age to understand the evolutionary status of the gas and to use this knowledge to tie the physical structure of the cloud to its evolutionary history.

In addition to the ground-based studies of cloud chemistry, I am also one of the co-investigators on the Submillimeter Wave Astronomy Satellite (SWAS). SWAS was operational from 1998-2005. SWAS is observing key atomic and molecular species that are believed to play an important role in the energy balance and chemistry of molecular clouds, but which are unobservable from the ground due to absorption by the Earth's atmosphere. The targeted species are water, isotopic water, molecular oxygen, atomic carbon, and isotopic carbon monoxide. Shown below is the detection of water in the molecular outflows of several young stars.

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