Debris Disks and Exo-planet Habitability
First Author:
Jane Greaves
Email: jsg5 AT st-andrews.ac.uk
University of St Andrews
Physics & Astronomy
North Haugh
St. Andrews KY16 9SS United Kingdom
Abstract
A census of Spitzer results for nearby Solar analogues shows that around 20 percent of these stars host debris at much greater levels than in the Solar System, and sometimes at ages older than the Sun. Any terrestrial planets could therefore be heavily bombarded for billions of years. We discuss the fraction of systems in which life might never evolve to an advanced state, in particular modelling the rate of catastrophic impacts (e.g. removing the crust and oceans) on exo-Earths in the Habitable Zone. This rate depends on the comet population and the interaction with giant planets, both of which can now be infered from data. We also consider how Spitzer upper limits constrain the fraction of 'clean' systems and estimate the distance to the closest 'safe system' for life to evolve around a Solar-type star.
