Abstract:

We live in a golden age of exoplanet discovery and characterization. The accelerating pace of discovery has revealed a great diversity of planetary compositions and system architectures that is only partially sampled in our Solar System. My talk will tour these exotic worlds with a focus on studies of ‘super-Earths’ and Neptune-size planets. From Doppler and transits surveys, we have learned that these small planets are the most abundant despite being the most difficult to detect. Their large numbers support the bottom-up picture of planet formation by core accretion, but also raise new questions about planet migration and protoplanetary gas depletion. With only a handful of well-measured super-Earths, we already see an order of magnitude range in bulk density. Using atmospheric spectroscopy and theoretical models, we are just beginning an exploration of the great diversity of super-Earth compositions ranging from gassy mini-Neptunes to iron-rich super-Mercuries, with diluvian water worlds in between.