UV - Optical spectral templates of local galaxies

Spectral templates of galaxies in the waveband from 1200 to 10000 Angstrom have been developed based on large aperture (10" x 20") IUE data combined with matched aperture optical data. Such templates are essential for understanding high redshift galaxies, which are observed in rest wavelengths in the ultraviolet effectively in large apertures because of their great distances. The templates are based on marphological classifications for elliptical, SO, Sa, Sb; Sc, and starburst galaxies according to extinction. These templates have been used in coordination with IR data, to determine dust properties in starburst galaxies (see Calzetti 1997). The distinguishing characteristic of the spectra in the region from 1200 a to 10000 Angstrom is their behaviour in the region from 3000 to 5000 Angstrom; with their colors in this narrow region ranging from red in the ellipticals to blue in the unreddened starbursts. The spectral templates of local galaxies are presented both from a close-up view of UV-optical spectra and in the larger context of the spectral energy distribution across the spectrum from radio, FIR, NIR, IR, optical, and UV, to X-ray. The bluest starburst galaxy, which has hydrogen line ratios consistent with no reddening, is compared with a model of age 20 Myr and suggestions are made about how to incorporate dust into the models in more realistic ways than the standard foreground dust with Milky Way extinction.