CPSH Seminar Series: Saugata Barat, The University of Texas at Austin
August 11, 2026
October 12, 2026 at 1:00pm CT
Location: Classroom 15.216B, Physics, Math and Astronomy Bldg.
UT Austin, Department of Astronomy
2515 Speedway, Stop C1400
Austin, Texas 78712-1205
Online: To join online contact Brandon Jones.
Get seminar links sent straight to your inbox, subscribe to our seminar mailing list.
Speaker: Saugata Barat, The University of Texas at Austin
Host: Caroline Morley
Title: Time-Lapse of Exoplanets: Watching Sub-Neptunes Evolve with JWST
Abstract: Sub-Neptunes and super-Earths are the most common type of exoplanets discovered so far in our galaxy, yet our own solar system does not have a direct analog. These worlds sit between Earth and Neptune in size, and their formation and evolution history still remain an unsolved puzzle.
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?
For the first time, JWST allows us to unravel the atmospheric composition of these mysterious sub-Neptunes with unprecedented precision. In this talk, I will present new JWST results for both young (<100 Myr) and mature (~Gyr) sub-Neptunes, compare their atmospheric compositions across age, temperature, and stellar irradiation, and discuss emerging patterns that hint at their origins. I will connect these insights to formation pathways and early evolutionary mechanisms, and conclude with the key open questions that will define the next decade of observations and modeling as we work towards understanding these low-mass rocky planets.
Biography: I am currently the CPSH postdoc fellow at UT Austin. Before this, I was a postdoc in MIT, and completed my PhD in March 2025 from the University of Amsterdam. My research focusses on observations of atmospheres of sub-Neptunes and super-Earths at different stages of their evolution. I use space based telescopes like Hubble and JWST to understand the origin and evolution of these planets. When I am not thinking about exoplanets I can be usually found cooking, reading or watching murder mysteries on Netflix!