Mass Loss from Super-Earths and Sub-Neptunes

I am extremeley interested in theories and observations of low mass planets, especially those with substantial atmospheres. Recent surveys like the Kepler mission have begun finding a new population of low-mass low-density (LMLD) transiting planets. These planets have masses between Earth and Neptune, but their large radii imply that they must have thick volatile atmospheres. Moreover, they are frequently found on highly irradiated orbits in multi-planet systems. Whether these planets are truly super-Earths (with hydrogen/helium atmospheres on) or instead sub-Neptunes (with substantial water layers as well) has fundamental implications for theories of planet formation and migration.

My advisor Jonathan Fortney and I work on developing models of planet evolution to try and better understand these planets. We examine the coupled thermal, tidal, and mass loss evolution of these LMLD planets to try and understand their composition and formation. In particular, we focus the possibiltiy that XUV driven mass loss may substantially change the composition of low mass planets. We use these models to examine the compositions and histories of specific systems like Kepler-11, and make predictions for the broader population of planets.

In the future we plan to develop more sophisticated mass loss and evolution models and combine these with formation population synthesis models in order to understand the entire formation and evolution history for low mass planets. In addition we are extremely interested in working with radial velocity follow-up surveys and transit-timing groups to increase the number of LMLD planets with measured densities that can then be studied in detail.