Astronomy Colloquium / Spring 2009

February 20

Prof. Phil Armitage

University of Colorado at Boulder

"Is our Solar System a typical planetary system?"

Most observed extrasolar planetary systems bear scant resemblance to our own, raising doubts as to whether the Solar System represents a typical outcome of planet formation. The most intriguing difference is the typically high eccentricity of extrasolar planet orbits, which is commonly attributed not merely to selection effects but rather to the dominance of different physical processes - slow scattering of a disk of left over debris in the Solar System versus violent instability among massive planets in extrasolar planetary systems. After reviewing the case for this interpretation of the observations, I will present results from a new and unprecedentedly large set of dynamical simulations of early planetary system evolution. The simulations suggest that both the Solar System and current extrasolar planetary systems can be understood as limiting cases of a single model, and that Solar System analogs may be very common among planetary systems with giant planets at large radii whose masses sum to a Jupiter mass or less.