We have investigated in some detail the physics of very low Z models with Z = 10-5. Even if we have little chance of observing such star populations, these models are most relevant for the early chemical evolution of galaxies. The models enable us to calculate the yields in CNO, He and heavy elements necessary to study the early evolution of galaxies. The diagrams showing log N/O vs. log O/H and log C/O vs. O/H are particularly powerful to infer properties of the early star generation in galaxies.
This work shows the large differences brought by the present models with rotation. In future we shall calculate the detailed yields of the various heavy elements.
Copyright ESO 2002