ULTRAVIOLET SPECTRAL EVOLUTION OF STAR-CLUSTERS IN THE IUE LIBRARY

The ultraviolet integrated spectra of star clusters and HII regions in the IUE library have been classified into groups based on their spect ral appearance, as well as on age and metallicity information from oth er studies. We have coadded the spectra in these groups according to t heir S/N ratio, creating a library of template spectra for future appl ications in population syntheses in galaxies. We define spectral windo ws for equivalent width measurements and for continuum tracings. These measurements in the spectra of the templates are studied as a functio n of age and metallicity. We indicate the windows with a strong metall icity dependence, at different age stages.