Collisional Evolution of Circumstellar Debris Disks

A large number of circumstellar debris disks have been observed and characterized by Spitzer. The dust seen in these systems must be the product of collisions among larger parent bodies, which are not detected directly. We will constrain the properties of these bodies by collisional modeling, using a multi-zone code with realistic scaling of collisional outcomes. Dust production rates and depletion lifetimes will be computed for a selected set of debris disks having well-defined luminosities and radial extents, orbiting a variety of stellar types. The results will constrain the total mass of each disk and the sizes of the unseen parent bodies that are the source of the observed dust. The stochastic nature of the collisional code will allow us to estimate the likelihood that the observed dust abundance represents a steady state or a transient event due to a giant impact. The impact velocities (i.e., orbital eccentricities) required to match the observed dust production may allow us to infer the presence of planets in these systems.