[PLS] Collin Cherubim (Harvard)

“Small planet evolution: helium worlds, oxygen worlds, and the discovery of a rocky exoplanet atmosphere”

The Kepler and TESS exoplanet surveys have taught us that the most common planetary formation pathway leads to sub-Neptunes: planets larger than Earth and smaller than Neptune. The compositions of sub-Neptunes remains poorly understood. I developed a planetary evolution model, IsoFATE, which simulates volatile exchange between an escaping atmosphere and evolving molten interior. I present recent results that show an oxidation gradient spanning the radius valley, with planetary atmospheres/interiors growing increasingly oxidized with decreasing radius and orbital period. IsoFATE predicted helium enrichment in the atmosphere of a terrestrial planet orbiting in the nearest liquid-water habitable zone of a quiet M star. I present results from a survey that tested and supported this hypothesis, revealing the first atmosphere on a temperate, terrestrial exoplanet and the first candidate helium world. Finally, I discuss ways in which the model predictions can be further tested to inform future observational surveys.

Planetary Lunch Seminar —

Colloquia topics span the range of research interests of the department’s planetary sciences research program, and the talks are intended to appeal to any graduate students, postdocs, research scientists, and faculty with a background in planetary science. Speakers include members of the MIT community and visitors.

Contact: planetary-org@mit.edu