Speaker: Roman Rafikov (Princeton)

Title: Metal-rich white dwarfs as signposts of planet formation

Abstract: 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 near the white dwarf. 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 circumstellar disk onto the white dwarf surface.