相关论文: SPINSTARS at low metallicities
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…
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…
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 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…
This article first reviews the basic physics of rotating stars and their evolution. We examine in particular the changes of the mechanical and thermal equilibrium of rotating stars. An important (predicted and observed) effect is that…
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…
Stellar winds from fast-rotating Population III (Pop III) stars have long been suspected to make important contributions to early metal enrichment, as features in the nucleosynthesis of such `spinstars' are consistent with the chemical…
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…
Whenever stars are rotating very fast (Omega/Omega_crit > 0.7, with Omega_crit the Keplerian angular velocity of the star accounting for its deformation) radiative stellar winds are enhanced in polar regions. This theoretical prediction is…
Rotation appears as a dominant effect in massive star evolution. It largely affects all the model outputs: inner structure, tracks, lifetimes, isochrones, surface compositions, blue to red supergiant ratios, etc. At lower metallicities, the…
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…
Rotation deeply affects the evolution of very metal poor massive stars. Indeed, even moderately rotating stars reach the break--up limit during the Main--Sequence (MS) phase, they evolve rapidly to the red after the core H--burning phase…
Massive stars are "cosmic engines" (cf the title of the IAU Symposium 250). They drive the photometric and chemical evolution of galaxies, inject energy and momentum through stellar winds and supernova explosions, they modify in this way…
We estimate the rotation speed of Population III (Pop III) stars within a minihalo at z ~ 20 using a smoothed particle hydrodynamics (SPH) simulation, beginning from cosmological initial conditions. We follow the evolution of the primordial…
We discuss three effects of axial rotation at low metallicity. The first one is the mixing of the chemical species which is predicted to be more efficient in low metallicity environments. A consequence is the production of important…
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…
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…
We discuss recent models on the evolution of massive stars at very low metallicity including the effects of rotation, magnetic fields and binarity. Very metal poor stars lose very little mass and angular momentum during the main sequence…
Mass loss is a determinant factor which strongly affects the evolution and the fate of massive stars. At low metallicity, stars are supposed to rotate faster than at the solar one. This favors the existence of stars near the critical…