Origins and Properties of Super-Earths and Neptune-size Planets
Andrew Howard



The currently observed architectures of extrasolar planetary systems trace the processes of planetary formation and evolution. Until recently, Jovian-size planets provided nearly all of the observational constraints. My talk will focus on several new probes of smaller planets -- super-Earths and Neptunes -- using Doppler detections with Keck, transit detections with Kepler, and atmospheric transmission spectroscopy. These studies demonstrate that small planets are the most abundant despite being the most difficult to detect. They support the bottom-up picture of planet formation by core accretion, but also raise new questions about the mechanisms of planet migration, the timing of protoplanetary gas depletion, and the effect of stellar mass on small planet formation. With only a handful of well-measured super-Earths, we already see an order of magnitude range in bulk density. With transit 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 exotic water worlds in between.