Revealing the Diversity and Formation of Super-Earths
Björn Benneke

The discovery of short-period planets with masses and radii between the ones of Earth and Neptune was one of the biggest surprises in the brief history of exoplanet science. From the Kepler mission, we now know that these “super-Earths” orbit at least 40% of stars, likely representing the most common outcome of planet formation. Despite this ubiquity, we know little about their typical compositions and formation histories. Spectroscopic transit observations can shed new light on these mysterious worlds by probing their atmospheric compositions. In this talk, I will present an overview of my ongoing 124-orbit (200-hour) Hubble Space Telescope program to reveal the chemical diversity and formation of super-Earths. This unprecedented survey provides the first comprehensive look at this intriguing new class of planets by probing seven planets ranging from 1 Neptune mass and temperatures as high as 2000K to a 1 Earth-mass planet near the habitable zone of its host star. I will discuss the field’s current state of knowledge, demonstrate our new techniques to observe extremely bright exoplanet targets with HST WFC3 and STIS, and present the first intriguing results from our survey. Finally, I will discuss the bright future of this kind of spectroscopic transit observations in the era of K2, TESS, and JWST.