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Astron. Astrophys. 350, 694-704 (1999) AcknowledgementsWe would like to thank Nicola Attico for interesting discussions. This work is partially supported by MURST and by ASI of Italy. ![]() ![]() ![]() ![]() © European Southern Observatory (ESO) 1999 Online publication: October 4, 1999 ![]() |