Debris disks in extrasolar planetary systems

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Over 220 nearby stars are now known to have extrasolar planets in orbit around them. A comparable number of stars are also known to be surrounded by belts of asteroidal and cometary debris. There is now an emerging population of stars that, like our own Sun, have both planets and debris in their systems. By studying this select bunch of 'planet-debris' stars we will be able to help work out how planetary systems form and evolve. One type of 'planet-debris' system this project will study is being seen at a time when the inner reaches of its planetary system are being bombarded by an unusually high quantity of debris. We may be witnessing these systems at an epoch akin to the period of 'Late Heavy Bombardment' in the solar system, a 50Myr event thought to have happened 3.8Gyr ago during which the Earth and Moon were subjected to an unusually large influx of comets. In another type of 'planet-debris' system, one (or more) Jupiter-like planets orbit much closer to the parent star than the debris, yet evidence for their influence may still be imprinted on the structure of the debris belt. That structure can be used to ascertain the history of the planetary system and provide evidence for as yet unseen planets orbiting the star. This project aims to study these planetary systems through a mixture of both observations and theoretical modelling. The information gained about these systems, and more generally about the physical processes which determine the final architecture of extrasolar planetary systems and the subsequent evolution of those systems, will help to answer some of the most enduring philosophical questions that mankind has posed. These include questions about how unique our solar system is, and how common planets are that, like our own Earth, are capable of sustaining life.