Abstract

Contributed Talk - Splinter ExoPlanets

Tuesday, 16 September 2025, 16:11

Tracking the Atmospheric and Interior Evolution of a Young Transiting Exoplanets System

Jean-Michel Désert
AIP

Young transiting exoplanets provide a rare window into planet formation and early atmospheric evolution. The V1298 Tau system (20 Myr) offers a rare glimpse of atmospheres still in their early stages. Using Hubble and JWST observations, we search and detect gas phase molecular species in their puffy hydrogen‑helium envelopes. Surprisingly, the atmosphere of V1298 Tau b appears poorer in heavy elements than expected, challenging the idea that bigger planets always have richer metallicities. The lack of methane hints at unusual chemistry, possibly driven by heat or strong mixing. Models suggest that over the next billion years, this giant planet could lose much of its atmosphere and shrink into a Neptune‑sized or even smaller world. V1298 Tau gives us a unique opportunity to study how young planets evolve and how their birth environments shape their futures.