相关论文: Nucleosynthesis in Rotating massive stars and Abun…
The first massive stars triggered the onset of chemical evolution by releasing the first metals (elements heavier than helium) in the Universe. The nature of these stars and how the early chemical enrichment took place is still largely…
At very low metallicity, the effects of differential rotation have a more important impact on the evolution of stars than at high metallicity. Rotational mixing leads to the production of great quantities of helium and of primary $^{14}$N…
We review some important observed properties of massive stars. Then we discuss how mass loss and rotation affect their evolution and help in giving better fits to observational constraints. Consequences for nucleosynthesis at different…
We examine the role of rotation on the evolution and chemical yields of very metal--poor stars. The models include the same physics, which was applied successfully at the solar $Z$ and for the SMC, in particular, shear diffusion, meridional…
Big Bang nucleosynthesis produces only light elements and the very first generation stars are thus formed from metal-free clouds. They start the production of heavy elements during their life, and enrich the interstellar medium through…
(Abridged) Rotation has been shown to play a determinant role at very low metallicity, bringing heavy mass loss where almost none was expected. Is this still true when the metallicity strictly equals zero? The aim of our study is to get an…
We present preliminary results of stellar structure and nucleosynthesis calculations for some early stars. The study (still in progress) seeks to explore the expected chemical signatures of second generation low- and intermediate-mass stars…
We investigate the role of stellar axial rotation on the nitrogen nucleosynthesis at low metallicities Z. For this purpose, we have calculated models with initial masses between 2 and 60 M$_\odot$ at Z=0.00001 from the zero age sequence to…
The main effect of axial rotation on the evolution of massive PopIII stars is to trigger internal mixing processes which allow stars to produce significant amounts of primary nitrogen 14 and carbon 13. Very metal poor massive stars produce…
We investigate the effect of new stellar models, which take rotation into account, computed for very low metallicities on the chemical evolution of the earliest phases of the Milky Way. We check the impact of these new stellar yields on a…
Although the theoretical study of very low metallicity (Z) and metal-free stars is not new, their importance has recently greatly increased since two related fields have been developing rapidly. The first is cosmological simulations of the…
The effects of rotation on low-metallicity stellar models are twofold: first, the models reach break-up during main sequence and may lose mass by mechanical process; second, strong internal mixing brings freshly synthesized elements towards…
The present paper discusses the main physical effects produced by stellar rotation on presupernovae, as well as observations which confirm these effects and their consequences for presupernova models. Rotation critically influences the mass…
The first stars might have been fast rotators. This would have important consequences for their radiative, mechanical and chemical feedback. We discuss the impact of fast initial rotation on the evolution of massive Population III models…
Some indirect observations, as the high fraction of Be stars at low metallicity, or the necessity for massive stars to be important sources of primary nitrogen, seem to indicate that very metal poor stars were fast rotators. As a…
Rotation was shown to have a strong impact on the structure and light element nucleosynthesis in massive stars. In particular, models including rotation can reproduce the primary nitrogen observed in halo extremely metal-poor (EMP) stars.…
Rotating massive stars at $Z=10^{-8}$ and $10^{-5}$ lose a great part of their initial mass through stellar winds. The chemical composition of the rotationally enhanced winds of very low $Z$ stars is very peculiar. The winds show large CNO…
Stellar rotation produces an internal mixing of the elements due to shear instability and meridional circulation. This leads to observable $N/C$ enhancements in massive stars above about 7--9 $M_{\odot}$. Rotation also favours mass loss by…
We review general characteristics of massive stars, present the main observable constraints that stellar models should reproduce. We discuss the impact of massive star nucleosynthesis on the early phases of the chemical evolution of the…
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 review, we first recall the effect…