Freiburg 2008 – wissenschaftliches Programm
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EP: Fachverband Extraterrestrische Physik
EP 8: The Sun and Heliosphere II
EP 8.6: Vortrag
Dienstag, 4. März 2008, 18:00–18:15, KGI-Aula
The modulation of Galactic Cosmic Rays in the Outer Heliosheath — Horst Fichtner1, Stefan Ferreira2, Marius Potgieter2, and •Klaus Scherer1 — 1Institut für Theoretische Physik,Lehrstuhl IV: Weltraum- und Astrophysik,Ruhr-Universität Bochum, D-44780 Bochum, Germany — 2Unit for Space Physics, North-West University, 2520, Potchefstroom, South Africa
The current paradigm of galactic cosmic ray propagation and modulation assumes that the outer boundary for these processes is the heliopause. We demonstrate here that low energetic galactic cosmic rays (< 100 MeV) are already modulated in the Outer Heliosheath, i.e. ahead of the heliopause. The reason is that the supersonic interstellar plasma flow undergoes a transition to a subsonic plasma at the bow shock. The plasma in the region between the bow shock and the heliopause, i.e. the Outer Heliosheath, is then heated, its turbulence levels increase, and the interstellar magnetic field is compressed. This leads to changes in the diffusion tensor in the Outer Heliosheath compared to that in the interstellar medium such that a decrease of the low energetic galactic cosmic ray intensities occurs already downstream of the bowshock. First results will be presented.