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Astron. Astrophys. 356, 118-126 (2000) AcknowledgementsThis work has made use of the Simbad database, operated at CDS, Strasbourg, France. Also this work is supported by National Natural Science Foundation of China. ![]() ![]() ![]() ![]() © European Southern Observatory (ESO) 2000 Online publication: March 28, 2000 ![]() |