Recent advances in instrument technology have allowed astronomers their first glimpses of the vestiges of young star formation, circumstellar disks around "T Tauri" stars. A study of both these disks and their central stars is expected to provide fundamental insights into the early evolution of our own solar system. The Principle Investigator (PI) will continue previous research in which he has used infrared and millimeter wavelength interometer arrays to resolve the disk around two T Tauri stars, including clumps of material having masses similar to the planet Jupiter's. In this renewal program the PI will extend his studies to fainter brightnesses and hence will be able to study a statistically stable sample of young stars. The goals are to understand which properties of stars influence disk properties and to examine how the disks evolve in subsamples of progressively older stars. A key question will be to identify the importance of a star's being in a "binary" (a pair of stars born at the same time and orbiting around one another). Current ideas hold that the presence of a close binary star will sweep away the matter from a star and prevent the formation of a disk and hence a system of planets. The PI will test early indications that closely-spaced binaries do not have disks and that single or widely-spaced binaries do. The PI will also extend his observational and data reduction techniques to the infrared-millimeter study of the center of our Galaxy, as well as to shocks in interstellar gas created by the collisions of external galaxies.
