1. Wolfgang Pauli Institute, c/o Faculty of Mathematics, Univ. of Vienna, Oskar-Morgenstern-Platz 1, A-1090 Wien, Austria
2. Faculty of Mathematics, Univ. of Vienna, Oskar-Morgenstern-Platz 1, A-1090 Wien, Austria
3. Institute for Astrophysics, Faculty of Physics, Univ. Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen, Germany
4. Department of Aerodynamics and Fluid Mechanics, Brandenburg University of Technology Cottbus-Senftenberg, D-03046 Cottbus, Germany
5. Department of Astronomy and McDonald Observatory, University of Texas at Austin, Austin, TX 78712, USA
6. Center for Astrophysical Plasma Properties, University of Texas at Austin, Austin, TX 78712, USA