Cool Dust and Gas in Transitional and Debris Disks

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In this project, Dr. Jonathan Williams (University of Hawaii) will study the line and continuum emission from circumstellar disks in the late stages of evolution, as they transition from an inner hole to a planet-forming debris system. Circumstellar disks are an inevitable by-product of star formation and the birthplaces of extrasolar planets. The formation of planets themselves generates additional dust that may be observed long after the star has formed and has settled onto the main sequence. Disks are readily detectable in the infrared but the emission is optically thick and is a poor measure of the mass, especially in the outer regions. Observations in the submillimeter regime allow total disk masses to be determined. Dust grain sizes are constrained from the slope of the energy distribution, imaging locates the larger particles that are influenced more by the gravity of a protoplanet than the radiation from the central star, and line observations reveal the disk kinematics. The program will be carried out using the James Clerk Maxwell Telescope and the Submillimeter Array, submillimeter observing facilities on Mauna Kea, Hawaii. In addition to the contribution this research will make in our understanding of the evolution of circumstellar disks, this work will also contribute to the education and training of students in areas of submillimeter astronomy and interferometry. The project will support the dissertation research of a graduate student and an undergraduate student will also participate in the project by assisting in observing runs on Mauna Kea and collating ancillary data on the observed disks. This project, with its implications for planet formation, will be of broad interest and the Dr. Williams will continue to give public talks in this field through an established outreach lecture series at the University of Hawaii's Institute for Astronomy.