Chemical evolution models with a new stellar nucleosynthesis

Abstract

Numerical models for the chemical evolution of the Galaxy have been computed with the new stellar yields published by Maeder (1992). These metallicity dependent yields represent an important improvement in the chemical evolution of galaxies but there are still uncertainties in the stellar evolution which prevent completely satisfactory results. {}From the comparison of the model predictions with the corresponding observational constraints we find that Maeder's nucleosynthesis reproduces the oxygen and carbon abundances and provides consistent $Δ$Y/$Δ$(O/H) ratios if a significant amount of gas is accreted by the galactic disc during its whole lifetime. The lower mass limit for the black hole formation (M$_{bh}$) must be larger than 22.5 M$_{\odot}$ to avoid oxygen underproduction.