Signposts of planetary systems around metal-rich white dwarfs
Recent Spitzer observations have revealed presence of near-IR excesses in spectra of more than a dozen of metal-rich white dwarfs. These excesses are naturally interpreted as resulting from reprocessing stellar emission by compact, optically thick disks of dusty debris. The prevalent idea for their origin is the tidal disruption of asteroids scattered by massive unseen planets providing evidence for existence of the latter around white dwarfs. This circumstellar material has also been proposed as the cause of high-Z element pollution of host white dwarf atmospheres. I will provide an overview of observations in this rapidly developing area, and will describe recent progress in understanding the transfer of high-Z material from the compact circumstellar debris disk onto the white dwarf surface.
Date: Jeudi, le 31 janvier 2013 Heure: 11:30 Lieu: Université de Montréal Pavillon Roger-Gaudry, local D-460 Contact: Patrick Dufour