New Insights into Cosmic-Ray-induced Biosignature Chemistry in Earth-like Atmospheres

• DOI: 10.3847/1538-4357/aacf03
• Publication Date: 2018-08-06T13:19:25Z
• Authors: Markus Scheucher; J. L. Grenfell; F. Wunderlich; M. Godolt; F. Schreier; H. Rauer
• Keywords: Planetary habitability

With the recent discoveries of terrestrial planets around active M-dwarfs, destruction processes masking possible presence life are receiving increased attention in exoplanet community. We investigate potential biosignatures having Earth-like (N$_2$-O$_2$) atmospheres orbiting habitable zone M-dwarf star AD Leo. These bombarded by high energetic particles which can create showers secondary at surface. apply our cloud-free 1D climate-chemistry model to study influence key particle shower parameters and chemical efficiencies NOx HOx production from cosmic rays. determine effect stellar radiation rays upon atmospheric composition, temperature, spectral appearance. Despite strong stratospheric O$_3$ rays, smog significantly build up lower atmosphere modeled planet Leo related low UVB. N$_2$O abundances decrease with increasing flaring energies but a sink reaction for excited oxygen becomes weaker, stabilizing its abundance. CH$_4$ is removed mainly Cl upper cases not via hydroxyl as otherwise usually case. Cosmic weaken role heating middle so that H$_2$O absorption more important. additionally underline importance HNO$_3$ marker showers. In nutshell, uncertainty influences biosignature