Abstract details

To derive the Star Formation History of stellar systems, we need sets of evolutionary tracks covering large range and thin grid of masses and metallicities. Up to now, our group has used the Padova 94 (Fagotto et al., 1994) tracks. This dataset satisfies the requierements concerning the mass range (0.6-120 M$_{\odot}$), but its metallicity grid (0.0004, 0.004, 0.008, 0.02, 0.05) is too coarse to reproduce the observational properties of some metal poor objects, like the galaxy SBS 1415+437 or the cluster BS90 in the SMC. To compare the SFH of different galaxies, we need to preserve the homogeneity of the physical inputs of the theoretical models, so that interpolation in metallicity between the computed tracks is required. We present here grids of models, with Z between 0.0004 and 0.008, generated with an interpolation algorithm in which a special care has been devoted to reproduce the fundamental properties of the evolutionary sequences. The interpolated tracks are compared to a set of stellar models with the same nominal metallicity from the (Pietrinferni et al. 2004) data base. Finally, we give an evaluation of the age and metallicity of the old cluster BS90 in the SMC (Sabbi et al. 2006, submitted) as an application of this new dataset.