The next generation stellar population synthesis library

Most of the analysis of absorption lines in galaxies is done in the Lick system, defined in the 1970's and 1980's by Faber, Burstein and collaborators. Working in this system is difficult, since it is based on low resolution spectra taken with a non-linear detector without flux-calibration. Due to intrinsic errors in the published indices the Lick system limits the accuracy with which one can analyse galaxy spectra. In the last 2 years we have observed a new stellar library to replace the Lick system. It consists of 1100 stars, covering a wide range in metallicity, abundance ratio, temperature and gravity, observed at a resolution of 2.0Å (9 for Lick) from 3500–7500Å, and calibrated in flux. With this library galaxy spectra can be analysed much more accurately than before, and in much more detail. Most important, the library now makes it possible to study absorption lines of galaxies at intermediate and high redshift, something which was impossible with the Lick system. With this library it will be possible for the first time to synthesise full Spectral energy distributions of galaxies in the optical based fully on observational spectra.