Abstract details

It recently became possible to recover the star formation history (SFH) using spectra integrated along a line of sight (STECKMAP, Ocvirk et al. 2006; and NBURSTS, Chilingarian et al. this conference). Essentially these methods are based on the comparison between the observed spectrum and synthetic spectra of stellar population (Le Borgne at al. 2004; Bruzual & Charlot, 2003; Vazdekis at al. 1999... ). The synthetic spectra are themselves built with either empirical or computed stellar libraries with different characteristics and quality (ELODIE, Prugniel & Soubiran, 2001; STELIB, Le Borgne 2005; BaSel, Lastennet, 2001; MILES, in preparation ... ). At the end, the accuracy of the synthetic population depends both on stellar libraries and on synthesis algorithms (physical assumptions, interpolation of the library). To assess the accuracy of the synthetic spectra we are inverting spectra generated with one tool with template generated with another tool and we invert observed spectra of Galactic globular clusters with age and metallicity known from HR diagrams. We also compare results obtained with various stellar libraries plugged in Pegase.HR. We discuss the first attempts to use a stellar library resolved at different degrees of Alpha/Fe enhancements.