Evolutionary sequences of stellar models with new radiative opacities. III. Z=0.0004 and Z=0.05

We present detailed tabulations of two large grids of stellar models with the extreme initial chemical composition [Z=0.0004, Y=0.230], and [Z=0.050, Y=0.352]. The models are computed with the most recent radiative opacities (OPAL) by Iglesias et al. (1992) and with the inclusion of overshoot from convective cores and envelopes according to the formalism by Bressan et al. (1981) and Alongi et al. (1991), respectively, and the revision made by Bressan et al. (1993a). These calculations represent the continuation of the series initiated with the paper by Bressan et al. (1993a) for the grid with [Z=0.020, Y=0.280] (the reference solar like abundance). The tracks are calculated for a wide range of initial masses from 0.6 M. to 120 M. and extend from the ZAMS till very advanced evolutionary phases. Specifically, low and intermediate mass stars are followed to the beginning of the TP-AGB, while massive stars are followed till the core C-ignition. The models of low and intermediate mass stars are calculated at constant mass, whereas those of massive stars are followed in presence of mass loss by stellar winds incorporating a suitable dependence on the metallicity. The results of all the models are given in extensive tables which summarize also the lifetimes of the various phases and the variations of surface abundances by dredge-up phenomena and mass loss by stellar wind. The salient features brought by the different metallicity and helium content are briefly outlined, with particular attention to the anomalous behaviour of the low mass, high metallicity stars in core He-burning and later phases. Such grids of evolutionary tracks are well indicated for studies of population synthesis in virtue of their large coverage of masses, evolutionary phases, and chemical composition. The high metallicity set is particularly suited to interpret the stellar content of bulges and elliptical galaxies.