Formation of the TRAPPIST-1 planets

by Dr Chris Ormel (Tsinghua University)

Tuesday 12 May 2020, 12:45 → 13:45 Asia/Shanghai

ONLINE

Abstract

The TRAPPIST-1 system presents many challenges to planet formation theory. It is an ultra-compact system where the seven planets are all very similar (around 1 Earth radius) with a composition that tends to be intermediate between "dry" and "water rich", and where planet formation was obviously efficient. We have previously argued that its properties are hard to understand from classical planet formation concepts, and sketched a new pebble-driven growth model (Ormel 2017), which we have now quantitatively investigated. The crucial feature of our scenario is that planetesimals form only in a narrow annulus just outside the water snowline, due to outward diffusion and condensation of water vapor. Once a planetesimal has grown large by pebble accretion and mergers, it starts migrating inwards and the process may repeat itself. Our results indicate that this formation mechanism is able to explain the moderate water fractions of the TRAPPIST-1 planets as well as their similar sizes.

Biography

Chris Ormel, Associate Professor at Tsinghua University

2008 - PhD University of Groningen, Netherlands
2008--2011 Max-Planck-Institute of Astronomy, Heidelberg
2011--2014 Hubble Fellow at University of California, Berkeley
2014--2019 Vidi Laureate (Independent research group leader), University of Amsterdam

Chair

Dr. Jiaxin Han

Division

Astronomy and Astrophysics

Other information

Meeting ID: 816 636 04090

Joining Link: https://us02web.zoom.us/j/81663604090