Speaker: Ann-Marie Madigan (CU Boulder)

Host: Jake Simon

Title: Explaining the Edge of our Solar System 

Abstract:The Solar System's Kuiper Belt, an icy debris field beyond the orbit of Neptune, has an observed “cliff" at 48-50 AU: a sharp drop in surface density of bodies unpredicted by theory. In this talk, I will explain the Kuiper Cliff via a new dynamical mechanism. Hypothesizing that the Kuiper Belt once extended far beyond its current edge, I'll show that gravitational torques between the circular orbits of outer Kuiper Belt members and those scattered outward onto eccentric orbits by the giant planets can drive the Kuiper Belt objects onto highly elliptical paths. At closest approach to the Sun, these bodies suffer strong gravitational encounters with the giant planets and ultimately scatter out of the Solar System. This inside-out mechanism of truncating a planetesimal disk may also naturally explain the halt to Neptune's outward migration early in the Solar System's evolution and the existence of detached bodies like Sedna.

Bio: Ann-Marie Madigan is a theoretical astrophysicist and associate professor at the University of Colorado Boulder. Her research spans from planetary dynamics in our Solar System and white dwarf pollution, to gravitational wave recoil kicks of supermassive black holes and galactic dark matter.