Stellar Evolution in the Early Universe

Abstract

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 nitrogen 14, carbon 13 and neon 22. 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 solar masses. Galactic chemical evolution models calculated with models of rotating stars better reproduce the early evolution of N/O, C/O and C12/C13. We calculated the weak s-process production induced by the primary neon 22 and obtain overproduction factors (relative to the initial composition, Z=1.e-6) between 100-1000 in the mass range 60-90.

8 pages, 4 figures, proceedings of IAU Symposium 255, "Low-Metallicity Star Formation: From the First stars to Dwarf Galaxies", L.K. Hunt, S. Madden & R. Schneider, eds

References in corpus (6)

• First stars VI - Abundances of C, N, O, Li, and mixing in extremely metal-poor giants. Galactic evolution of the light elements
• C, N, O Abundances in the Most Metal-Poor Damped Lyman alpha Systems
• A new imprint of fast rotators: low 12C/13C ratios in extremely metal-poor halo stars
• Discovery of a massive variable star with Z=Zo/36 in the galaxy DDO 68
• Stellar Evolution at Low Metallicity
• Developments in physics of massive stars