Abstract for Proposal AST 94-21145 P.I.: Robert C. Kennicutt University of Arizona The objective of this project is to obtain data on the large-scale star formation properties and evolutionary properties of nearby galaxies. Such data provide essential ingredients for understanding and modeling the evolution of galaxies, and for understanding the physical processes that drive this evolution. They also provide the opportunity to develop and test the diagnostic methods needed to interpret observations of more distant galaxies at cosmological lookback times. Specific projects to be carried out include the following: 1) The determination of the star formation histories of galactic disks as a function of Hubble type and radius within individual galaxies, based on Ha and broadband surface photometry of 30 spiral galaxies. 2) A study of the systematic properties of OB/HII associations in spiral galaxies, based on a combination of groundbased imaging and spectroscopy and imaging with the Hubble Space Telescope. 3) An observational study of the stellar populations and star formation properties of galactic mergers. 4) An investigation of the form of the star formation rate vs. gas density law in disks, based on CCD observations of a complete sample of nearly spirals. Gravitational threshold and self-regulating star formation models will be tested. 5) Studies of the dynamics of the ionized interstellar gas in Magellanic irregular galaxies. These are directed at measuring the dynamic interactions between massive stars and the interstellar medium, and the role of large-scale winds and flows in the evolution of dwarf galaxies.
