This award supports Dr. Edward B. Churchwell and a graduate student of the University of Wisconsin to collaborate with Dr. Malcolm Walmsley of the Max-Planck Institute for Radioastronomy in Bonn, Germany. They are studying the conditions under which massive stars form and subsequently evolve by investigating the remaining molecular gas in which the star is embedded and the star's interaction with it. In particular, they will test the bow shock hypothesis by observing carefully selected molecular and atomic lines that probe the ionized and molecular gas. These observations will be obtained from observations at observatories in the U.S., Spain and Germany. This project is an important extension of the ongoing research of Dr. Churchwell that would not be possible without collaboration. Dr. Walmsley is an acknowledged expert on the interstellar medium in general and particularly on the computation and interpretation of the physical conditions in interstellar molecular and ionized gas clouds. These areas are particularly important to their joint research. He also provides convenient access to the 100 m telescope operated by the MPI in Germany and brings expertise in using the specialized instruments. He will also collaborate closely in developing detailed models of the molecular gas. Dr. Churchwell offers expertise in VLA measurements and will use interferometric instruments like the VLA in New Mexico to make observations in the US to study these objects with high spatial resolution. Massive stars are formed in dense condensations of molecular gas inside of giant molecular clouds. They play a crucial role in the energetics of galaxies and the interstellar medium, but their formation and early evolution are poorly understood. This project will contribute new insights into the formation of such massive stars by obtaining detailed physical parameters and spatial distribution of the surrounding hot gas.
