2024/09/17 by Félix Sainsbury-Martinez, Sainsbury-Martinez, Felix, Catherine Walsh +3 · 1 citation
Physics and Astronomy · #Astro and Planetary Science #Astronomy and Astrophysical Research #Earth and Planetary Astrophysics (astro-ph.EP) #FOS: Physical sciences #Stellar, planetary, and galactic studies
paper · pdf · doi:10.48550/arxiv.2409.11151
openalex publication_date 2024/09/17 · openalex created_date 2024/10/24 · openalex updated_date 2026/07/28
Impacts by rocky and icy bodies are thought to have played a key role in shaping the composition of solar system objects, including the Earth's habitability. Hence, it is likely that they play a similar role in exoplanetary systems. We investigate how an icy cometary impact affects the atmospheric chemistry, climate, and composition of an Earth-like, tidally-locked, terrestrial exoplanet, a prime target in the search for a habitable exoplanet beyond our solar system. We couple a cometary impact model which includes thermal ablation and pressure driven breakup with the 3D Earth System Model WACCM6/CESM2, and use this model to investigate the effects of the water and thermal energy delivery associated with an R=2.5 km pure water ice cometary impact on an Earth-like atmosphere. We find that water is the primary driver of longer timescale changes to the atmospheric chemistry and composition by acting as a source of opacity, cloud ice, and atmospheric hydrogen/oxygen. The water opacity drives heating at ∼5×10-4 bar, and cooling below, due to a decreased flux reaching the surface. The increase in atmospheric hydrogen and oxygen also drives an increase in the abundance of hydrogen/oxygen rich molecules, with the exception of ozone, whose column density decreases by ∼10%. These atmospheric changes are potentially observable for ∼ 1-2 years post-impact, particularly those associated with cloud ice scattering. They also persist, albeit at a much reduced level, to our quasi-steady-state, suggesting that sustained bombardment or multiple large impacts have the potential to shape the composition and habitability of terrestrial exoplanets.