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Abstract EANA2024-84


Photochemical production of pre-biotic molecule C2H2 in gaseous exoplanet atmospheres

Nidhi Bangera (1), Christiane Helling (1), Gloria Guilluy(2), Patricio Cubillos(1), Luca Fossati(1), Paolo Giacobbe(2), Paul Rimmer(3) & Daniel Kitzmann(4)
(1) Space Research Institute, Austrian Academy of Sciences, Schmiedlstrasse 6, 8042 Graz, Austria (2) INAF – Osservatorio Astrofisico di Torino, Via Osservatorio 20, 10025, Pino Torinese, Italy (3) Cavendish Laboratory, University of Cambridge (4) University of Bern


Photochemistry plays a crucial role in the formation of pre-biotic species in planetary atmospheres, driven by the interaction of stellar radiation with atmospheric constituents. Recent observations, such as the discovery of photochemically produced sulfur dioxide (SO₂) in the atmosphere of the exoplanets WASP-39b and WASP-107b, highlight the impact of photochemical reactions in such environments. We employ a photochemical-kinetic model to simulate the atmospheric chemistry of the gas giant exoplanet WASP-69b, focusing on three variables: initial elemental abundances, temperature-pressure conditions, and vertical mixing. Our results show that the pre-biotic molecule acetylene (C₂H₂) and larger hydrocarbons are preferentially produced in carbon-rich, high-temperature environments. However, the interplay between the variables reveals degeneracies, complicating the prediction of atmospheric chemistry trends. These findings highlight the importance of photochemical pathways in the production of pre-biotic species and provide insights into the potential habitability and chemical diversity of exoplanetary atmospheres.