相关论文: On the possible existence of a self-regulating hyd…
It has been known for a long time (Mestel~1953) that the meridional circulation velocity in stars, in the presence of mu-gradients, is the sum of two terms, one due to the classical thermal imbalance (Omega-currents) and the other one due…
The lithium plateau observed in halo stars has long appeared as a paradox in the general context of the lithium abundance behavior in stellar outer layers. First, the plateau is flat, second, the lithium abundance dispersion is extremely…
In the presence of rotation-induced mixing, element diffusion still occurs in stellar radiative zones, although at a slower rate than in the case of a complete stability of the stellar gas. As a consequence, helium settling leads to…
The observations of light elements in the Sun and Solar type stars give special clues for understanding the hydrodynamical processes at work in stellar interiors. In the Sun 7Li is depleted by 140 while 3He has not increased by more than…
We present a first set of results concerning stellar evolution of rotating low-mass stars. Our models include fully consistent transport of angular momentum and chemicals due to the combined action of rotation induced mixing (according to…
In the first paper of this series, we discussed analytically, in an approximate way, the mixing processes which occur in slowly rotating stars when the feed-back effects due to the diffusion-induced $\mu$-gradients are introduced in the…
In the two previous papers of this series, we have discussed the importance of t he $\mu$-gradients due to helium settling on rotation-induced mixing, first in a n approximate analytical way, second in a 2D numerical simulation. We have…
Time-dependent meridional circulation and differential rotation in radiative zones are central open issues in stellar evolution theory. We streamline this challenging problem using the downward control principle of atmospheric science,…
An explanation is presented for the rather strong total surface differential rotation of the observed very young solar-type stars like AB Dor and PZ Tel. Due to its rapid rotation a nonuniform energy flux leaves the stellar core so that the…
Meridional circulation in stratified stellar/planetary interiors in the presence of stable molecular weight gradients remains poorly understood, thereby affecting angular momentum transport in evolutionary models. We extend the downward…
We derive the effective temperatures and gravities of 461 OB stars in 19 young clusters by fitting the H-gamma profile in their spectra. We use synthetic model profiles for rotating stars to develop a method to estimate the polar gravity…
Current observations indicate that stars with higher rotation rates appear to maintain more surface lithium, and the majority of lithium-rich giants are indeed red clump stars. Hence, we investigate the mechanisms behind lithium enrichment…
(Abridged) We present a detailed analysis of the main physical processes responsible for the transport of angular momentum and chemical species in the radiative regions of rotating stars. We focus on cases where meridional circulation and…
We look for a simple analytic model to distinguish between stellar clusters undergoing a bimodal hydrodynamic solution from those able to drive only a stationary wind. Clusters in the bimodal regime undergo strong radiative cooling within…
The element settling due to the combined effects of gravity, thermal gradient, radiative acceleration and concentration gradient may lead to important abundance variations inside the stars, which cannot be neglected in the computations of…
Mean-field hydrodynamics advanced to clear explanations for the origin and properties of the global meridional flow in stellar convection zones. Qualitative arguments and analysis of basic equations both show that the meridional circulation…
Chemical turbulent mixing induced by rotation can affect the internal distribution of mu near the energy-generating core of main-sequence stars, having an effect on the evolutionary tracks similar to that of overshooting. However, this…
Transport processes occurring in the radiative interior of solar-type stars are evidenced by the surface variation of light elements, in particular Li, and the evolution of their rotation rates. For the Sun, inversions of helioseismic data…
There has been recent progress in the study of the angular momentum evolution of low mass stars (Krishnamurthi et al 1997a). Theoretical models can now be constructed which reproduce the angular momentum evolution of low mass open cluster…
We derive a new expression for the coefficient $D_{\mathrm{h}}$ of diffusion by horizontal turbulence in rotating stars. This new estimate can be up to two orders of magnitude larger than given by a previous expression. As a consequence the…