New Molecular Probes of Astronomical Sources (Interstellar Sources, Comets)

224 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1986.Three molecules were examined to evaluate their potential for refining the knowledge of astronomical molecular sources. The primary project involved HCO in interstellar molecular clouds. The observational results include the verification of the identity of interstellar HCO, the confirmation of the C('+)-HCO correlation first suggested by Snyder, Hollis, and Ulich (1976, Ap. J. (Letters), 208, L91), and the detection of an HCO abundance enhancement in the HII-molecular cloud interface region. Comparisons of these results to current molecular cloud models show good agreement between the observed and theoretical abundances.The second project consisted of a search for the HCN dimer in interstellar molecular clouds. (HCN)(,2), which is bound by van der Waals forces, represents a class of molecules which is not currently considered in interstellar clouds. No detections were made in the nine sources searched for (HCN)(,2) emission, and a comparison between (HCN)(,2) and HCN for Ori A indicates that the HCN dimer abundance is insufficient to appreciably affect the chemistry of the interstellar medium.Interpretation of the observational results from comets, which may contain information about the pre-solar molecular cloud, is hindered by the lack of detailed information about a comet's coma. The third project involved using the Very Large Array to observed 18 cm OH emission at high resolution in Comets Austin and p/Crommelin. Although no OH emission was directly detected with the VLA, this result, when combined with the single-dish detections of these comets, indicates a relative smooth OH coma that is extended on the scale of 10('5) km.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD