Dust and Gas in Debris Disks Reveal the Origins of Planetary Systems

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This award will fund studies to obtain and analyze observations of gas and dust that are found in flattened disks around some stars. These disks are called debris disks and represent the end stage of circumstellar disk evolution, with stellar ages corresponding to the epoch when giant planets in our solar system were newly formed. The investigators will use the ALMA (Atacama Large Millimeter/submillimeter Array), SMA (Submillimeter Array) and CARMA (Combined Array for Research in Millimter-wave Astronomy) telescopes and obtain spectra of three bright, nearby, edge-on debris disks that contain higher amounts of gas than is predicted by most models of planet formation. Their data will be used to test whether this gas is more likely to be primordial or produced from evaporating comets. The data will also be used measure the dynamical state of the debris disks, which will provide information about collisional velocities in the disk, which will be useful for constraining disk models and for detecting the presence of Neptune-mass planets in the disks. The principal investigator will buld a new protected infrastructure at Van Vleck Observatory, which is designed to accommodate demand from the surrounding community to learn about astronomical research. They will also incorporate public-level research talks by students and faculty, and hands-on astronomy explorations with the larger goal of increasing scientific literacy of the community members. This project will provide critical tests of the leading planet-formation models of our solar system and other planetary systems. Spatially resolved interferometric spectra of multiple gas lines and continuum emission will be obtained and analyzed from dust in three disk systems that have the dust properties of optically thin debris disks, yet retain substantial reservoirs of molecular gas detectable at millimeter wavelengths: 49 Ceti, HD 21997, and HD 14159. They will measure the total mass in each system, estimate its lifetime, and measure the basic chemical composition of each disks through multi-transition analysis of gas lines. In particular, they will observe multiple CO and HCN rotational lines, along with continuum bands. The data will also be used to test collisional evolution models, measure the velocity dispersion and the mass of largest bodies stirring the planetesimal population in the disks.