We would like to thank Dr R.N. Smartt, the T.A.C. of NSO/SP and the staff of the Sacramento Peak Observatory for their warm hospitality and their help with the observations. We would also like to thank Dr. J-P. Delaboudiniere for his support and constant interest. Finally we would like to thank J. Gurman, C. Delannee, H. Dara and J-F Hochedez for their contribution in JOP057 program. The anonymous referee contributed substantially in the improvement of the paper. This work has been supported in part by a grant from the Greek General Secretariat for Research and Technology.
© European Southern Observatory (ESO) 1999
Online publication: December 4, 1998