We are grateful to the ISO-SWS instrument teams of Vilspa in Villafranca (Spain) and SRON Groningen (NL) for their assistance in the data reduction at many stages during this research. In particular we thank Bart Vandenbussche for providing a spectrum of the standard star Lyrae, to check our reduction method. ACAB thanks NWO for an SIR scholarship to visit NASA Ames Research Center in Moffet Field (USA), where the analysis was started. This work is partially supported by NASA grants NAG5-3999 and NAGW-4039.
© European Southern Observatory (ESO) 1998
Online publication: July 7, 1998