Spectral evolution of stellar populations using isochrone synthesis

We combine the photometric model of isochrone synthesis recently published by Chariot and Bruzual (1991) with an updated library of stellar spectra to predict the spectral evolution of stellar populations with solar metallicity. The library of spectra assembled here supersedes other existing libraries by its spectral range, its complete coverage of the color-magnitude diagram, and its inclusion of observed near-infrared spectra out to 2.56 micron. Also, the spectra are distributed on the stellar evolutionary tracks using optical/near-infrared color calibrations, as an improvement over models that used a single color of the effective temperature of the stars alone. The spectroscopic results obtained here confirm and extend the previous photometric predictions of the isochrone synthesis models while including the recent revision of evolutionary tracks for stars between 1.3 and 2.5 solar masses by their authors.