LP791-18d as a case study for outgassing rocky exoplanets

Over the past three decades, the discovery of over five thousand exoplanets has opened avenues for atmospheric characterization, now feasible for a select subset through spectroscopic observations paired with Bayesian inference techniques. These exoplanetary atmospheres serve as crucial windows into planetary formation and evolutionary histories. Achieving accurate interpretations demands a comprehensive approach, advancing theory and modeling to understand the continuous interplay between exoplanetary atmospheres and their surrounding environments—both lower and upper boundaries. This project focuses on rocky exoplanets situated near their host stars, often exhibiting states of magma oceans or heightened volcanic activity due to proximity and tidal forces from neighboring planets. These unique candidates offer enhanced opportunities for observing the ongoing production of secondary atmospheres through outgassing processes. We present a holistic modeling framework for understanding interior-atmosphere interactions and predict the atmospheric footprint of the planet's interior based on its oxidation state. Moreover, we assess the detectability using the James Webb Space Telescope (JWST) and propose a spectral index capable of inferring the oxidation state of a planet's interior.