A Stellar Library for Evolutionary Synthesis Modeling Including Variable AGB Stars

A self-consistent spectrophotometric modelling of intermediate age post-starburst requires accurate stellar ingredients taking into account a principal feature of the stars dominating the near-IR emission during this phase: the variability of the AGB stars. A new library of stellar spectra based on averages of the empirical spectra of variable AGB stars is presented. This library is designed for convenient use in the population synthesis models. We discuss meaningful ways to compute these averages, and the non-trivial connection with the theoretical stellar parameters. Our library covers the near infrared wavelength range between 0.5 micron and 2.5 micron and exhibits fundamental differences when compared to the standard libraries using only static giants.