Stellar Evolution in the Early Universe
نویسندگان
چکیده
Massive stars played a key role in the early evolution of the Universe. They formed with the first halos and started the re-ionisation. It is therefore very important to understand their evolution. In this paper, we describe the strong impact of rotation induced mixing and mass loss at very low Z. The strong mixing leads to a significant production of primary N, C and Ne. Mass loss during the red supergiant stage allows the production of Wolf-Rayet stars, type Ib,c supernovae and possibly gamma-ray bursts (GRBs) down to almost Z = 0 for stars more massive than 60 M⊙. Galactic chemical evolution models calculated with models of rotating stars better reproduce the early evolution of N/O, C/O and C/C. We calculated the weak s-process production induced by the primary Ne and obtain overproduction factors (relative to the initial composition, Z = 10) between 100-1000 in the mass range 60-90.
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