Lightning initiation on the exoplanet K2-18b

Abstract

Abstract Recent JWST data provide a basis for investigations into exoplanetary atmospheres at novel high precision. Weather and climate on these planets, along with the implications of the observed atmospheric composition for extraterrestrial life, remain hotly debated. Using photochemical modelling data based on JWST observations as inputs for a thoroughly validated plasma simulation code, we present the first simulations of streamers, precursors of lightning, in an exoplanetary atmosphere. We find the electrical breakdown field magnitude in this atmosphere to be approximately half that of Earth, indicative of an atmosphere more susceptible to lightning than our own. We show that lightning can incept on K2-18b in all three tested atmospheric configurations, and that variations in atmospheric composition, in particular in the presence of water vapour, affect the rate of streamer inception.