Time: 3:30 pm
Location: ABB 102
Guest: Dr. James Wadsley
Professor, McMaster University
Title: Asteroids from pebbles: Early stages of planet formation
Our understanding of planet formation has changed dramatically with the discoveries of young stellar systems with disks, the large population of extra-solar planets and new behaviours of mixtures of gas and dust present in young proto-planetary disks. Planet formation begins with the micron-sized dust found in the interstellar medium. In disks it collides to form up to almost metre-sized grains that feel drag that sends them rapidly into the star which would seemingly end planet formation. The streaming instability is a general behaviour of gas and dust mixtures that enhances the dust density locally. Dust rich regions soon reach densities where gravity collapses them into loose rubble piles with properties similar to those of asteroids and icy outer solar system bodies. These are too large to suffer from drag and can go on to form planets. I present results including recent work by graduating students Josef Rucska and Rishita Gudapati on the streaming instability and implications for proto-planetary disks, asteroids and planet formation.