Exploring the Mysterious Origins of Super-Earths and Mini-Neptunes

Nearly a decade has passed since the discovery that planets with sizes intermediate between that of the Earth and Neptune (“super-Earths” or “mini-Neptunes”, depending on their densities) dominate the observed population of close-in exoplanets. These planets have no solar system analogue, yet a significant fraction of Sun-like stars appear to have at least one (and often more) interior to Mercury’s orbit. Did they form in situ, or did they migrate inward from a more distant formation location? Which planets lost their primordial atmospheres, and which kept them? In my talk I will describe current efforts to address these questions by characterizing the bulk densities and present-day mass loss rates of these planets. I will also explore the role that outer gas giant companions might play in shaping the properties of inner planetary systems.