Cool Stars 14 - Submitted Abstract # 354
This version created on 05 October 2006

Atmospheric erosion caused by stellar coronal plasma flows on
terrestrial exoplanets within close-in habitable zones of low mass
stars


Helmut Lammer, Space Research Institute,  Austrian Academy of Sciences, Schmiedlstr. 6, A-8042 Graz, Austria
Maxim Khodachenko, L., Space Research Institute, Austrian Academy of Sciences, Schmiedlstr. 6, A-8042 Graz, Austria
Yuri Kulikov, N., Polar Geophysical Institute (PGI), Russian Academy of Sciences, Khalturina Str. 15, Murmansk, 183010, Russian Federation
Herbert Lichtenegger, I. M., Space Research Institute,  Austrian Academy of Sciences, Schmiedlstr. 6, A-8042 Graz, Austria
Naoki Terada, National Institute of Information and Communications Technology, Nukui-Kitamachi, Koganei, Tokyo, and CREST, Japan Science and Technology Agency, Saitama, Japan
Thomas Penz, Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Palermo Giuseppe  S. Vaiata, Palermo, Italy

Low mass M stars show a higher level of stellar activity compared to
solar-like stars, and because of the close orbital distance of their
habitable zones (HZs) compared to that of the Solar System,
terrestrial exoplanets within M star HZs will be much stronger
influenced by stellar winds and dense plasma ejected from the host
star by Coronal Mass Ejections (CMEs).  The efficiency of atmospheric
erosion of CO2-rich exoplanets, with the size and mass similar to that
of the Earth, due to dense stellar plasma flows within close-in
habitable zones of active M-type dwarf stars is investigated.  Since
M- stars are active at the X-ray and EUV radiation wavelengths over
long time periods we have applied a thermal balance model at various
XUV flux input values for simulating the thermospheric heating by
photodissociation and ionization processes, due to exothermic chemical
reactions and cooling by the CO2 IR radiation in the 15 micron band.
Our study shows that intense XUV radiation of active M-stars results
in atmospheric expansion and extended exospheres.  Using thermospheric
neutral and ion densities calculated for various XUV fluxes, we
applied a numerical test particle model for the simulation of
atmospheric ion pick up loss rates from an extended exosphere of
magnetized and non-magnetized Earth-like exoplanets and discuss the
consequences of our results for the evolution of habitable planets
within active M star environments.  

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