Ralph Pudritz is a theoretical astrophysicist at McMaster University, whose research focuses on star and planet formation, and origins of life. Ralph completed his Ph.D. at UBC under the supervision of Greg Fahlman, completing it in 1980. He took an NSERC postdoctoral Fellowship to the Institute of Astronomy in Cambridge (1980-1982). He joined the faculty in the Dept of Physics and Astronomy at McMaster University in 1986 after further postdoctoral work at U.C. Berkeley and Johns Hopkins University. He has been involved in many aspects of Canadian as well as international astronomy and astrophysics, including chairing Canada's first decadal survey of Astronomy and Astrophysics - the NRC-NSERC Long Range Planning Panel (LRP2000). Ralph is the founding (2004-2015) Director of McMaster's Origins Institute (OI).
Title: Connecting Exoplanet Properties to Planet Formation: a New Paradigm Emerges
Abstract: One of the great challenges facing planet formation is to understand how essential planetary properties – their masses, orbital characteristics, bulk properties and atmospheric compositions – are connected to their formation in host protoplanetary disks. Recent JWST observations of water and other molecules in protoplanetary disks as well the atmospheres of evolved exoplanets show that the composition of planets cannot be understood as a consequence of their formation at one place in the disk. Forming planets accrete pebbles, planetesimals, and gas with a wide range of chemical compositions as they move through their evolving disks. An essential process that controls disk chemistry, evolution, and planetary migration is how angular momentum is removed from disks. Recent theoretical work, as well as ALMA and JWST observations, show that MHD disk winds (observed as ubiquitous jets and outflows in protostellar systems) and not the traditionally assumed disk turbulence play the dominant role. This has led to a new paradigm for planet formation that I will explore in this talk. Our work shows that disk wind driven evolution has profound effects on planet formation and planetary populations. An excellent test of such models is in understanding the origin of the radius valley that separates mini-Neptunes from superEarths, with which I will conclude my talk.