[PLS] Saugata Barat (MIT)

“Time-Lapse of Exoplanets: Watching Sub-Neptunes Evolve with JWST”

Sub-Neptunes are the most common type of exoplanets in the Galaxy, yet our own solar system does not have one. These worlds sit between Earth and Neptune in size, and their diversity makes them prime targets for understanding planetary habitability with upcoming missions such as the Habitable Worlds Observatory (HWO). Therefore, understanding their formation and evolution history is of utmost importance.

Two competing formation pathways have been proposed. In the gas-dwarf scenario, sub-Neptunes form in-situ, accumulating puffy H/He atmospheres that subsequently evolve through intense mass loss, cooling, and contraction. Alternatively, they could form further out as volatile-rich worlds that migrate inward. Distinguishing between these scenarios requires answering several fundamental questions: What is the atmospheric composition of sub-Neptunes? How do young and mature sub-Neptune atmospheres compare with each other? How diverse are sub-Neptunes immediately after formation? What physical processes govern early evolution and on what timescales?

JWST allows us to unravel the atmospheric composition of these mysterious sub-Neptunes with unprecedented precision. In this talk, I will present latest JWST observations for both young (<100 Myr) and mature (~Gyr) sub-Neptunes to constrain the nature and atmospheric composition of these worlds for the first time, and start addressing the aforementioned questions. I will compare their atmospheric compositions across age, test how atmospheric composition and chemistry of sub-Neptunes evolve, and discuss what it implies for their interior structure. I will discuss how these results are challenging standard formation and evolution models of sub-Neptunes and conclude with key open questions that will inspire the next decade of observations and modelling as we work towards understanding the most common planets in our Galaxy.

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