White Dwarf Debris Disks and the Fate of Planetary Systems
Ted von Hippel
Siena College

After a brief introduction to white dwarfs and debris disks, I will present observations from the Spitzer Space Telescope and ground-based telescopes of metal-polluted white dwarfs with circumstellar debris disks. We measure the constituents of the debris disks, the elemental abundances of the material being accreted, and the accretion timescale. Our measurements support the idea that disruptions of asteroids created these debris disks. Based on the properties of these stars, I interpret the majority of the metal-polluted white dwarfs as resulting from planetary system bodies being ground down during the late stages of stellar evolution.

Date:	Thursday, 16 April 2009
Time:	12:30
Where:	Université de Montréal
	Pavillon Roger-Gaudry, local D-460
Contact:	Pierre Bergeron