We thank F. Bensch, A. Burkert, and J. Stutzki for useful discussions. V.O. acknowledges support by the Deutsche Forschungsgesellschaft through the grant SFB 301C. Computations were performed at the Rechenzentrum Garching of the Max-Planck-Gesellschaft. ZEUS was used by courtesy of the Laboratory for Computational Astrophysics at the NCSA. This research has made use of NASA's Astrophysics Data System Abstract Service.
© European Southern Observatory (ESO) 2000
Online publication: December 8, 1999