Signposts of planetary systems around evolved stars.

Roman Rafikov (Princeton) - October 6, 2014 at 12:10 pm

Recent Spitzer observations have revealed presence of near-IR excesses in spectra of more than thirty white dwarfs with atmospheres enriched in metals. 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. Accurate measurements of abundances of different elements in these atmospheres give us a unique chance to measure the bulk compositions of extrasolar minor objects. I will provide an overview of observations in this rapidly developing area, and will describe recent progress in our understanding of the transfer of high-Z material from the compact circumstellar debris disk onto the white dwarf surface.

The seminar will be held in B-1 Hearst Field Annex.


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