Gaia-ESO Survey: empirical and synthetic Lick/SDSS indices for stellar population studies

Abstract

Stellar population study is fundamental for the understanding of the physical process involved in the formation and evolution of galaxies. Out of several approaches to get information about abundance patterns in stellar population the use of broad and narrow spectral features of indices (e.g Lick/IDS system) is one of the most widely used. The large amount of data available nowadays allow to compute empirical libraries which are a fundamental tool for studying integrated spectra of stellar systems. Here, we present an empirical library of Lick-like spectral indices (ELickSDSSv2), computed using the spectra of the Gaia-ESO survey (GES). The library includes also the spectral indices of a previous version which was computed from Elodie, Miles, Indo-US, and FEROS spectra. Since empirical libraries carry on the imprints of the local properties of the solar neighbourhood, it is mandatory to complement them with synthetic libraries to reproduce integrated spectra of system whose star formation histories are different from those of local systems. Preliminary results of a new synthetic Lick/SDSS library are also presented.