Ph.D., University of Chicago, 1977

Professor & Chairman, Department of Astronomy, University of Floridaversity of Florida

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My research emphasizes the determination of the detailed structure of circumstellar disks around fairly young stars, those less than a few tens of millions of years old. Disks around stars younger than a million years old are likely still coalescing into planets, and determination of the disk structure provides constraints on the planet-forming environment, particularly the densities and temperatures of the coalescing solids and the shape of the disk. After a few million years or so, much of the primordial disk material, that is, that material left over from the original cloud that formed the star and disk, is used up or blown away, and the disk is converted to a so-called debris disk made of dust created from the collisions of the larger bodies - either large dust particles or planetesimals - that were formed during the earlier phase of the disk evolution. Determination of the disk structure at this phase tells us about those collisional processes, which are still important in the disk evolution. Recently I have begun using the technique of mid-IR polarimetry to determine the structure of magnetic fields in protoplanetary disks and star-forming regions.