This work was partly supported by Fondecyt 1971064 and DI UdeC 97.11.20-1. Support for this work was also provided by the National Science Foundation through grant number GF-1002-98 from the Association of Universities for Research in Astronomy, Inc., under NSF Cooperative Agreement No. AST-8947990. C. Sterken acknowledges a research grant of the Fund for Scientific Research Flanders (FWO).
© European Southern Observatory (ESO) 1999
Online publication: November 23, 1999