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EP: Fachverband Extraterrestrische Physik

EP 9: Exoplanets und Astrobiology with poster prize talk

EP 9.2: Hauptvortrag

Donnerstag, 22. März 2018, 11:30–12:00, BSZ - Pabel HS

New Insights into Cosmic Ray induced Biosignature Chemistry in Earth-like Atmospheres — •Markus Scheucher¹, John Lee Grenfell², Mareike Godolt¹, and Heike Rauer^1,2 — ¹Technische Universität Berlin, 10623 Berlin, Germany — ²Deutsches Zentrum für Luft- und Raumfahrt, 12489 Berlin, Germany

With the recent discoveries of terrestrial planets around active M-dwarfs, better understanding of atmospheric responses to the stellar environment becomes of high importance. We investigate the habitability and potential biosignatures of planets having Earth-like (N₂-O₂ dominated) atmospheres orbiting in the habitable zone of quiet and active M-dwarf stars. Such atmospheres are strongly bombarded by high energetic particles, such as Galactic Cosmic Rays and Stellar Energetic Particles. We study the effect of stellar radiation and the incoming energetic particle fluxes upon atmospheric composition, temperature, and spectral information, by varying secondary particle production profiles and NOx(=N+NO+NO₂+NO₃) and HOx(=H+HO+HO₂) chemical production efficiency, in a cloud-free 1D climate-chemistry model. Our results show that uncertainties in flaring strength and particularly atmospheric chemical production efficiency of NOx and HOx from cosmic rays can become important for determining biosignature signals for terrestrial planets around active M-dwarfs. We further show that this is especially the case for high flaring scenarios where weakened water, methane, and ozone features followed by HNO₃ build-up may even become detectable in the future in primary transit spectra.