Evolutionary Stellar Population Synthesis at 2 A Spectral Resolution

In this paper we develop an evolutionary stellar population synthesis model to predict spectral energy distributions, SED’s, for single-age, single-metallicity stellar populations, SSP’s, at resolution ∼1.8˚A in two narrow, but very important spectral regions around 4000˚A and 5000˚A. The input stellar database is composed of a subsample of ∼550 stars, selected from the original KPNO coude feed stellar spectral library of Jones. Therefore, this is the first time that an evolutionary model employs such an extensive empirical stellar spectral library, at such high resolution, for supporting its SED’s predictions. A spectral library corresponding to simple old stellar populations with metallicities in the range −0.7 ≤ Fe/H ≤ +0.2 is presented here, as well as an extensive discussion about the most popular system of absorption indices at intermediate resolution, the Lick system, showing the advantages of using the new model predictions. Also, for the first time is shown the behavior of the system of indices of Rose, at higher resolution, as a function of the age and metallicity of the stellar population. The newly synthesized model spectra can be used to analyze the observed galaxy