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Ann. Geophys., 25, 145-159, 2007
www.ann-geophys.net/25/145/2007/
© European Geosciences Union 2007
Aspects of solar wind interaction with Mars: comparison of fluid and hybrid simulations
N. V. Erkaev1, A. Bößwetter2, U. Motschmann2, and H. K. Biernat3
1Institute for Computational Modelling, Russian Academy of Sciences, 660036, Krasnoyarsk, Russia
2Institute for Theoretical Physics, TU Braunschweig, Germany
3Space Research Institute, Austrian Academy of Sciences, Graz, Austria
Abstract. Mars has no global intrinsic magnetic field, and consequently the
solar wind plasma interacts directly with the planetary
ionosphere. The main factors of this interaction are:
thermalization of plasma after the bow shock, ion pick-up process,
and the magnetic barrier effect, which results in the magnetic
field enhancement in the vicinity of the obstacle. Results of
ideal magnetohydrodynamic and hybrid simulations are compared in
the subsolar magnetosheath region. Good agreement between the
models is obtained for the magnetic field and plasma parameters
just after the shock front, and also for the magnetic field
profiles in the magnetosheath. Both models predict similar
positions of the proton stoppage boundary, which is known as the ion
composition boundary. This comparison allows one to estimate
applicability of magnetohydrodynamics for Mars, and also to check
the consistency of the hybrid model with Rankine-Hugoniot
conditions at the bow shock. An additional effect existing only in
the hybrid model is a diffusive penetration of the magnetic field
inside the ionosphere. Collisions between ions and neutrals are
analyzed as a possible physical reason for the magnetic diffusion
seen in the hybrid simulations.
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