Toward Maps of Exoplanet Surfaces

Perhaps the simplest question that one can ask of a distant star or planet is, "What does it actually look like?" Even the best interferometers can only give us limited information about the surfaces of select giant and/or nearby stars, while the direct imaging of exoplanet surfaces is all but impossible. Fortunately, several techniques exist that allow us to indirectly infer what the surfaces of stars and exoplanets look like from precise photometric light curves and high resolution spectral timeseries. In this talk, I will review previous approaches to mapping the surfaces of stars as well as recent results in the nascent field of exocartography. I will discuss the mathematical theory behind the mapping problem, including its degeneracies and limitations, and present several novel approaches to producing surface maps of stars and exoplanets. Finally, I will show how these maps can be used to learn about the physics of stellar surfaces, the dynamics of gas giant atmospheres, and surface processes on solar system objects. I will end with a look to the future, showing how these techniques can pave the way to the characterization of terrestrial exoplanets in the habitable zones of their stars with upcoming instrumentation.