Detecting planetary geochemical cycles on exoplanets: Atmospheric signatures and the case of SO2 - Astrophysics > Earth and Planetary AstrophysicsReport as inadecuate




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Abstract: We study the spectrum of a planetary atmosphere to derive detectable featuresin low resolution of different global geochemical cycles on exoplanets - usingthe sulphur cycle as our example. We derive low resolution detectable featuresfor first generation space- and ground- based telescopes as a first step incomparative planetology. We assume that the surfaces and atmospheres ofterrestrial exoplanets Earth-like and super-Earths will most often bedominated by a specific geochemical cycle. Here we concentrate on the sulphurcycle driven by outgassing of SO2 and H2S followed by their transformation toother sulphur-bearing species which is clearly distinguishable from the carboncycle which is driven by outgassing of CO2. Due to increased volcanism, thesulphur cycle is potentially the dominant global geochemical cycle on drysuper-Earths with active tectonics. We calculate planetary emission, reflectionand transmission spectrum from 0.4 to 40 micrometer with high and lowresolution to assess detectable features using current and Archean Earth modelswith varying SO2 and H2S concentrations to explore reducing and oxidizinghabitable environments on rocky planets. We find specific spectral signaturesthat are observable with low resolution in a planetary atmosphere with high SO2and H2S concentration. Therefore first generation space and ground basedtelescopes can test our understanding of geochemical cycles on rocky planetsand potentially distinguish planetary environments dominated by the carbon andsulphur cycle.



Author: L. Kaltenegger, D. Sasselov

Source: https://arxiv.org/







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