The Structure and Evolution of Molecular Clouds

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Dr. Blitz will investigate how the interstellar medium evolves from the diffuse state which is characteristic of most of its volume into the dense molecular state from which stars are formed. He will perform detailed observations of small molecular clouds without star formation which are found preferentially at high galactic latitudes, and which appear to have ages of less than 3,000,000 years. These young objects are imbedded in the atomic gas sheaths out of which the molecular clouds condensed, and Dr. Blitz hopes to identify the reasons why some parts of the atomic gas becomes molecular in these relatively simple clouds. He will make detailed comparative studies of the gas and dust associated with two giant molecular clouds that seem to be in different evolutionary states in order to understand how the structure of a giant molecular cloud evolves with time. Dr. Blitz will also explore the role of the molecular gas in the nuclei of Seyfert galaxies. In the fundamental stellar cycle, where the interstellar gas is collected into stars ultimately to be enriched with heavy elements and ejected back into interstellar space, one of the least well understood phases is the evolution of the diffuse gas into dense, star forming molecular clouds. We currently know very little about how the diffuse interstellar medium collects itself into giant molecular clouds and how these molecular clouds ultimately fragment into individual stars and clusters of stars. Dr. Blitz' research aims to illuminate the physical mechanisms by which the interstellar medium is prepared for the formation of new stars. That is, he seeks to understand how diffuse gas ultimately forms dense proto-stellar cores, the evolution of which as been aggressively investigated by many workers.