Event Time: Monday, September 23, 2019 | 3:00 pm - 4:00 pm
Event Location:
Hennings 318
Add to Calendar 2019-09-23T15:00:00 2019-09-23T16:00:00 Planets Big and Small Event Information: 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. Observations report a comparable population of sub-Saturns as Jupiters, contrary to the expectation of the model of runaway gas accretion. I will discuss the importance of hydrodynamic considerations in halting the runaway. Finally, 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. Event Location: Hennings 318