Encouraging discussions and helpful suggestions by E. Müller are acknowledged. We are grateful to A. Mezzacappa for a careful and critical refereeing of the paper and for updating us with the most recent improvements of his code. This work was partially supported by the Japanese Society for the Promotion of Science (JSPS), Postdoctoral Fellowships for Research Abroad, and by the Supercomputer Projects (No.97-22 and No.98-35) of the High Energy Accelerator Research Organization (KEK). H.-T.J. was supported, in part, by the Deutsche Forschungsgemeinschaft under grant No. SFB-375. The numerical calculations were mainly done on the supercomputers of KEK.
© European Southern Observatory (ESO) 1999
Online publication: March 18, 1999