Abstract

Contributed Talk - Splinter ExoPlanets

Wednesday, 17 September 2025, 14:18

Exploring the Chemistry of Exoplanet Atmospheres: Forward Modeling with XODIAC and NEXOTRANS in the era of JWST and ARIEL

Priyankush Ghosh, Sambit Mishra, Debayan Das, Shubham Dey, Liton Majumdar
National Institute of Science Education and Research, Jatni 752050, Odisha, India

With the advent of missions like JWST and the forthcoming ARIEL, exoplanetary research has entered a transformative era, providing an abundance of atmospheric data spanning a vast range of planetary environments. Yet, current observational capabilities primarily detect a handful of simple molecules, including H2O, CO2, CH4, and SO2, leaving the broader chemical diversity, among carbon-, nitrogen-, sulfur-, and phosphorus-bearing species, largely unexplored. Addressing this gap requires sophisticated forward models that integrate high-temperature photochemistry, intricate chemical kinetics, and radiative transfer processes. In this work, we introduce XODIAC, a Lagrangian-based photochemical-kinetics model featuring an extensive chemical network applicable over temperatures from ~100 K to 30,000 K. Coupled with our in-house radiative transfer code, NEXOTRANS, XODIAC enables the prediction and identification of new molecular species from observations across multiple wavelengths. We further illustrate how this approach allows us to constrain elemental abundances (C/H, N/H, O/H, S/H, P/H) and infer tracer ratios such as C/O, N/O, S/O, and P/O, for constraining planetary formation histories and migration scenarios.