Natural Sciences
Life Sciences
Scientific Computing
Life Science

Sarah Rugheimer, St Andrews Centre for Exoplanet Science, University of St. Andrews, Scotland

MPI for Astronomy, Lecture Hall, Königstuhl 17

HIFOL Origins of Life

Abstract: When we observe the first terrestrial exoplanet atmospheres, we expect to find planets around a wide range of stellar types, UV environments, and geological conditions. Since the first exoplanets available for characterization will be likely for M dwarf host stars, understanding the UV environment of these cool stars is a vital step in understanding the atmospheres of these planets (Rugheimer et al., 2015). Additionally the atmospheres of these planets will not been fixed in time. Earth itself offers many possible atmospheric states of a planet. We set out to examine how an Earth-like planet at different geological epochs might look around other star types (Rugheimer Kaltenegger, 2018). Additionally, we examine the plausibility of detecting prebiotically interesting molecules, such as HCN, NH3, CH4, and C2H6 in an early-Earth type atmosphere around stars with very different UV environments, an M dwarf and a solar analogue. We find that some of these molecules could be produced abiotically in a CO2/CH4/H2 rich atmosphere with lighting and photochemistry. These molecules would be interesting to detect in an exoplanet atmosphere since they are known to be useful for key prebiotic chemical pathways. HCN, for example, is present at each of the initial photochemical reactions that produce lipids, amino acids and nucleosides, the three building blocks of life (Patel et al. 2015). We also look at the rise of oxygen and the detectability of combinations of biosignature gases throughout Earth history, modeling the great oxygenation event and Neoproterozoic oxygenation event around other star types. We show the VIS - IR spectral features, with a focus of the influence of the host star and UV stellar environment on the detectability of prebiotic and biosignatures in terrestrial exoplanet atmospheres.

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