Physical Society Colloquium

Planets Big and Small

Eve Lee

Department of Physics
McGill University

From gas-poor Earths to gas-rich Jupiters, planets come in a variety of sizes. I will describe the physics behind the diversity of exoplanets — how the core and gas assembly processes give rise to the observed distribution of radii and orbital periods. Basic astrophysical considerations of gas dynamical friction, gravitational scattering, collisional mergers, and gas accretion by cooling inform us that planets smaller than Neptune likely emerged in situ, in the late stages of disk evolution. Larger planets on the other hand must have nucleated from massive cores that assemble in the early stages of disk evolution. I will show how the theory of star-disk-planet interaction can describe the observed planet occurrence rate as it varies across orbital periods, planet radii, and stellar metallicities.