A. Zavagno is grateful for the support of an ESA external fellowship and thanks J. Caplan for his careful reading of the manuscript. D. Lorenzetti and P. André are thanked for many fruitful discussions. The authors would like to thank the James Clerk Maxwell Telescope staff, in particular Wayne Holland, for their assistance during the observations. The James Clerk Maxwell Telescope is operated by The Observatories on behalf of the UK PPARC, the Canadian NRC and the Netherlands ZWO. This research has made use of the Simbad database, operated at CDS, Strasbourg, France.
© European Southern Observatory (ESO) 1997
Online publication: April 28, 1998