Speaker: Dr. Yanqin Wu, Professor and Associate Undergraduate Chair, University of Toronto Department of Astronomy and Astrophysics
Title: "From exoplanets back to dust grains"
Abstract: I will introduce, briefly, the current demographics of extra-solar planets, pointing out a couple results that provide more direct insights into their formation in proto-planetary disks.
I will then zoom in to one critical quantity, the size of dominant dust grains in these disks. This quantity determines both the fate of disks and the formation pathway for planetesimals. It is, however, subject to both theoretical uncertainties and observational degeneracies. I will use both individual disks and ensemble disks to argue for the so-called 'small-grain hypothesis', that grains in disks have not grown to much beyond 100-microns, far below the pebble sizes required for rapid formation of planetesimals. If true, other formation pathways need to be investigated.
