The dynamic heliosphere, variable cosmic environments and their imprints in Earth s archives

The first meeting was held from 18. - 22. April 2005.
The next meeting will be held from 27. - 31. March 2006.

(Klick on the heliopshere to see a movie)


During its orbit around the galactic center the heliosphere reacts to the changes in the interstellar medium. In addition the interstellar medium may vary substantially, when the solar system passes through galactic spiral arms with increased star formation rate and hence a possibly increased cosmic ray flux.  During the past thousand to millions of years the cosmic ray fluxes could be monitored in the terrestrial cosmogenic isotopes, which are born in the atmosphere by the bombardment with cosmic rays and then deposited in sediments, ice cores, meteorites etc. Therefore the cosmogenic isotopes can be used as tracers of the cosmic ray flux at Earth. Because cosmic rays are strongly modulated during their propagation through the heliosphere, the sophisticated cosmic ray transport model, developed by the South African group, shall be used and combined with the hydrodynamic five-fluid Bonn model of the large-scale heliosphere to describe the state and dynamics of the heliosphere during the past. As input to these models the cosmic ray flux required for the observed cosmogenic isotope production rate shall be used. This model will be tested against the observations from spacecraft (e.g. Ulysses), concerning the relevant heliospheric parameters, like solar wind states and high energetic particle fluxes. Based on this information the past galactic environment around the solar system will be reconstructed with help of the cosmogenic archives.

Team members:

Klaus Scherer (lead),  Universität Bochum, D-44780 Bochum, Germany
Jürg Beer, EAWAG,  133 Dübendorf, CH-8600, Switzerland
Hans-Jörg Fahr,  Universität Bonn, 53121 Bonn,  Germany,
Stefan Ferreira, North-West University, Campus Potchefstroom, South Africa
Horst Fichtner, Ruhr-Universität Bochum, 44780 Bochum,  Germany
Bernd Heber, Christian-Albrechts-Universität, D-24118 Kiel, Germany
Ulrich Langner, North-West University, Campus Potchefstroom,  South Africa,
Jozef Masarik, Komensky University, Bratislava, Slovakia
Marius Potgieter, North-West University, Campus Potchefstroom, South Africa
Nir J. Shaviv, Hebrew University Jerusalem,  91904 Israel
Jan Veizer, University of Ottawa, Ontario K1N 6N5, Canada
Ararat Yeghikyan, Byurakan Astrophysical Observatory, Byurakan 378433, Armenia

Frank Arnold Ruprecht-Karls-Universität, 69120 Heidelberg, Germany
Ulrike Lohmann ETH Zürich, Switzerland