Planet Formation Post-Kepler

The message of the Kepler space mission is this: super-Earths abound in the universe.  These are planets 1 - 4 Earth radii and 2 - 20 Earth masses, composed of solids and gas in proportions of 100:1 by mass.  We describe how super-Earths/sub-Neptunes form within circumstellar disks of gas and dust.  From basic astrophysical considerations of gas dynamical friction, gravitational scatterings and mergers, and atmospheric accretion by cooling, we infer a planet formation history that occurs largly in-sutu, and late in the life of a protoplanetary disk.  We show how the theory explains observed occurrence rate trends with orbital period, and can be expanded to accommodate rarer sub-populations such as sub-Saturns (a.k.a. "super-puffs") and Jupiters.  Puzzles and prospects will be highlighted.

Speaker: Hao Cao, Harvard