We acknowledge the availability of the Jacoby et al's stellar library from the NDSS-DCA Astronomical Data Center. This work was supported in part by the Formation and Evolution of Galaxies network set up by the European Commission under contract ERB FMRX-CT96-086 of its TMR programme. B.M.P. acknowledges the receipt of a grant from the Department of Physics of the University of Pisa.
© European Southern Observatory (ESO) 1997
Online publication: April 28, 1998