The authors thank H.J. Habing for his encouragements of this collaboration and the referees (Drs. Feast and Whitelock) for constructive suggestions. P.R. Wood is acknowledged for comments on the pulsation modes of AGB variables. The research of J. Hron, F. Kerschbaum and M. Schultheis is supported by the Austrian Science Fund projects P9638-AST and S7308. Y.K. Ng thanks the Institut für Astronomie der Universität Wien and the department of Astronomy from the University of Padova, where part of this research was carried out, for their hospitality. The university of Wien provided financial support for Ng's research visit to Vienna and ANTARES, an astrophysics network funded by the HCM programme of the European Community, supported Ng's research visits to Padova. At the IAP-CNRS and at the Padova Astronomical Observatory the research of Ng was supported by respectively HCM grant CHRX-CT94-0627 and TMR grant ERBFMRX-CT96-0086 from the EC.
© European Southern Observatory (ESO) 1998
Online publication: September 14, 1998