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 131A Campbell Hall.
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