Michiel Lambrechts: Understanding the formation of our Solar System in an...

Michiel Lambrechts is an associate professor working in the StarPlan section of the Globe Institute at the University of Copenhagen (Denmark). My aim is to improve our understanding of the various processes that lead to the formation of planets around our Sun and other stars. An important part of my research has been focused on pebble accretion: the mechanism by which protoplanets grow in mass by sweeping up small mm-sized icy/rocky pebbles that are observed to be omnipresent in young protoplanetary discs. Michiel Lambrechts' professional web-site Abstract: This talk will cover our current view on how planets, like Earth, grow large in protoplanetary discs. These discs, composed of gas and dust, surround young stars for a few million years after their formation. Starting with microscopic dust particles, solids efficiently grow through coagulation to larger mm-sized particles for which fragmentation becomes important. These pebbles then radially drift inwards, through gas drag, within the disc lifetime. During their radial trek inwards, a significant fraction of the tens to hundreds of Earth-masses of pebbles gets either trapped in dense pebble swarms that get converted to planetesimals, or directly accreted by large planetesimals that act as planetary embryos. Depending on the available mass budget in pebbles, these cores then grow into Earth-like, super-Earths or even gas-giant planets. Putting this all together, we will compare the outcome of this theoretical model to the currently-known exoplanet census, our Solar System, and discuss implications -specifically with respect to volatile delivery - to the composition of habitable-zone planets.