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Astron. Astrophys. 346, 831-842 (1999) AcknowledgementsWe thank H. Tsunemi, J. Vink, E. Miyata and K. Nomoto for helpful information and discussions. This work was supported by the SFB-375 "Astroparticle Physics" of the Deutsche Forschungsgemeinschaft.
© European Southern Observatory (ESO) 1999 Online publication: June 17, 1999 ![]() |