Speaker
Description
The interpretation of exoplanet spectra obtained with JWST typically assumes that observed atmospheres are in steady state. In this work, we challenge that assumption by demonstrating that stellar flares can induce rapid and long-lasting changes in atmospheric composition that directly impact observables. We model the effects of recurrent stellar flaring on metal-rich exoplanet atmospheres using time-dependent photochemistry and radiative transfer. We find that flare activity drives strong variability in key molecules such as SO₂, CO₂, CH₄, and H₂O, producing spectral changes at the tens to hundreds of parts-per-million level, well within JWST sensitivity. Extreme flares can temporarily suppress molecular features, while cumulative flaring leads to persistent compositional shifts on decadal timescales. These results imply that JWST spectra do not necessarily probe a planet’s equilibrium state, but rather a snapshot conditioned on recent stellar activity. Atmospheric retrievals must therefore account for temporal variability to avoid biased inferences of composition and climate, especially for planets orbiting active stars.
| Talk category | NOVA Network 2 |
|---|---|
| Second preference | Plenary |
