Affiliation: | Division of Theoretical Astrophysics, National Astronomical Observatory, Mitaka, Tokyo 181, Japan; Department of Theoretical Astrophysics, A. F. Ioffe Physico-Technical Institute, St Petersburg 194021, Russia; Institut für Theoretische Physik der Universität Frankfurt am Main, Postfach 11 19 32, 60054 Frankfurt/Main 11, Germany; Department of Earth and Space Science, Faculty of Science, Osaka University, Toyonaka, Osaka 560, Japan |