Cool Stars 14 - Submitted Abstract # 305
This version created on 05 October 2006

Biomarker Response to Galactic Cosmic Ray-Induced NOx and the Methane


Lee Grenfell, Deutsches Zentrum fuer Luft- und Raumfahrt (DLR), Berlin, Germany
Jean-Mathias Griessmeier, Observatoire de Paris, Meudon, France
Beate Patzer, Technisches Universitat, Berlin, Germany
Heike Rauer, Deutsches Zentrum fuer Luft- und Raumfahrt (DLR), Berlin, Germany
Antigona Segura, Penn State (presently at IPAC CALTECH), USA
Anja Stadelmann, Technisches Universitat, Braunschweig, Germany
Barbara Stracke, Deutsches Zentrum fuer Luft- und Raumfahrt (DLR), Berlin, Germany
Ruth Titz, Deutsches Zentrum fuer Luft- und Raumfahrt (DLR), Berlin, Germany
Philip von Paris, Deutsches Zentrum fuer Luft- und Raumfahrt (DLR), Berlin, Germany

Planets orbiting in the habitable zone (HZ) of M-Dwarf stars are
subject to high levels of cosmic rays which produce nitrogen oxides in
earthlike atmospheres.  We investigate to what extent this NOx may
perturb biomarker signals.  Our model results suggest that the
biomarker signals are robust, changing in the M-star atmospheric
column by up to 25% due to the GCR NOx effects compared to an M-star
run without GCR effects and can therefore survive at least the effects
of galactic cosmic rays.  We have not however investigated stellar
cosmic rays here.  Methane (CH4) levels are about x1000  times higher
than on the Earth related to a lowering in hydroxyl (OH) in response
to changes in UV, as already noted in previous studies.  The high CH4
levels produce a large greenhouse effect of 50-60K which has a
potentially large effect upon the biomarker columns.  

----------------------------------