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Chemical Composition and Behavior of Super-Earth and Mini-Neptune Exoplanet Hazes

Presentation #213.02 in the session “Exoplanets and Systems: Giant Planet Atmospheres 2”.

Published onOct 26, 2020
Chemical Composition and Behavior of Super-Earth and Mini-Neptune Exoplanet Hazes

Exoplanet discoveries increase rapidly thanks to Kepler and TESS, and dedicated observational and modeling efforts are ongoing to characterize these newly discovered exoplanetary atmospheres. In this context, laboratory experiments to understand the chemical and microphysical processes at work in such atmospheres is a crucial complementary avenue of investigation. The properties of photochemical hazes formed in exoplanets impact their role in atmospheric chemistry, energy transport, and dynamics. Additionally, it is critical to understand the subsequent possible effect of hazes on observations, both for current platforms like Hubble and in the future with JWST and ground-based observatories. We characterized haze particles produced in the JHU PHAZER (Planetary HAZE Research) chamber with conditions relevant to temperate (300–600 K) exoplanet atmospheres from terrestrial to mini-Neptune. We obtained the composition of the laboratory exoplanet haze particles with elemental analysis and very high resolution mass spectrometry. We detected complex molecular species with general chemical formulae CwHxNyOz in the haze particles, including those of prebiotic interest, such as the formulae for a variety of amino acids, nucleobases, and simple sugars. The high oxygen content of these exoplanet haze analogues shows that certain oxygen carrier molecules readily participate in haze chemistry. Additionally, we observed that the exoplanet haze analogues exhibit diverse solubility properties, which may help us understand their role as potential cloud condensation nuclei and their role in subsequent atmospheric evolution.

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