A DATA-BASE FOR GALAXY EVOLUTION MODELING

This paper represents a collective effort to provide an extensive elec tronic data base useful for the interpretation of the spectra and evol ution of galaxies. A broad variety of empirical and theoretical data i s discussed here, and the data are made fully available in the AAS CD- ROM Series, Vol. 7. Several empirical stellar libraries are part of th is data base. They cover the ultraviolet spectral range observed with IUE, optical data from different ground-based telescopes, and ground-b ased infrared data. Spectral type coverage depends on the wavelength, but is mostly complete for types O to M and luminosity classes V to I. A large metallicity range is covered as well. Theoretical libraries o f selected spectral indices of cool stars and of stellar continuum flu xes in the temperature range 2000-50,000 K as well as Wolf-Rayet energ y distributions are presented. Several libraries of star clusters and early-type galaxies have been selected for this data base. We discuss an extensive set of empirical spectral templates covering the waveleng th region from 1200 to 9800 Angstrom, as well as narrow-band line indi ces in a large number of passbands. Bench-mark spectra of nearby galax ies for model tests are included as well. We compiled numerous evoluti onary models and isochrones for stars of all mass ranges of interest, wide metallicity range, and for all evolutionary phases, including the pre-main-sequence phase. The majority of the models have been compute d by the Geneva and Padova groups. Evolutionary synthesis models compu ted by several independent groups are made available. They can be appl ied to old and young systems, and are optimized with respect to differ ent aspects of input physics. The model predictions include stellar (c olors, magnitudes, absorption features) and nebular (emission-line flu xes) properties. Finally, we present models of ionized gas to be used for the interpretation of active galactic nuclei and young star-formin g galaxies. The community is encouraged to make use of this electronic data base and to perform a critical comparison between the individual datasets.