Related papers: Overshooting by convective settling
Recent developments in asteroseismology -- thanks to space-based missions such as {\it CoRoT} and {\it Kepler} -- provide handles on those properties of stars that were either completely inaccessible in the past or only poorly measured.…
We investigate the influence of convective overshoot on stellar evolution models of the thermal pulse AGB phase with M_ZAMS = 3 Msol. An exponential diffusive overshoot algorithm is applied to all convective boundaries during all…
The early evolution of planetary systems is expected to depend on various periods of disk matter accretion onto the central star, which may include the accretion of metal-rich matter after the star settles on the main sequence. When this…
A region of a star that is stable to convection according to the Ledoux criterion may nevertheless undergo additional mixing if the mean molecular weight increases with radius. This process is called fingering (thermohaline) convection and…
Overshooting and semiconvection are among the most uncertainties in the evolution of massive stars. Complete mixing over a certain distance beyond the convective boundary (Stothers \& Chin 1985) and an exponentially decaying diffusion…
By simulating jet-inflated bubbles in cooling flows with the PLUTO hydrodynamic code we show that mixing of high entropy shocked jet's material with the intra-cluster medium (ICM) is the major heating process perpendicular to the jets'…
Context. The Sun is a privileged laboratory of stellar evolution, thanks to the quality and complementary nature of available constraints. Using these observations, we are able to draw a detailed picture of its internal structure and…
We study the dynamical regimes of a density-stratified fluid confined between isothermal no-slip top and bottom boundaries (at temperatures $T_t$ and $T_b$) via direct numerical simulation. The thermal expansion coefficient of the fluid is…
We investigate the evolution of super-AGB thermal pulse (TP) stars for a range of metallicities (Z) and explore the effect of convective boundary mixing (CBM). With decreasing metallicity and evolution along the TP phase, the He-shell flash…
In recent years much interest has been shown in the process of thermohaline mixing in red giants. In low and intermediate mass stars this mechanism first activates at the position of the bump in the luminosity function, and has been…
Rotational velocity, lithium abundance, and the mass depth of the outer convective zone are key parameters in the study of the processes at work in the stellar interior, in particular when examining the poorly understood processes operating…
(abridged) Recent analyses have reported low lithium but high beryllium abundances on the solar surface; however, standard solar models (SSMs) predict Li abundances that are ~30$\sigma$ away from the observed value. In this study, we aim to…
We discuss the effect of chemical separation as matter freezes at the base of the ocean of an accreting neutron star, and argue that the retention of light elements in the liquid acts as a source of buoyancy that drives a slow but continual…
Based on the turbulent convection model (TCM), we investigate chemical mixing in the bottom overshooting region of the convective envelope of intermediate-mass stars, focusing on its influence on the formation and extension of blue loops in…
I summarize the stellar side of the cosmological lithium problem(s). Evidence from independent studies is accumulating and indicates that stars may very well be fully responsible for lowering their surface lithium from the predicted…
The lithium present in the photospheres of solar-type stars is transported to the inner parts by convection, reaching regions even somewhat below the convection zone, by non-standard transport mechanisms. In stars with deeper convective…
Mixing processes such as convection, overshooting and rotational mixing have long been known to affect the evolutionary properties of low-mass stars. While modeling a 1.2 Msun star, we encountered a semiconvective region outside the fully…
In stellar evolution calculations, the local pressure scale height is often used to empirically constrain the amount of convective core overshoot. However, this method brings unsatisfactory results for low-mass stars (< 1.1 -1.2 Mo for Z=…
Active galactic nuclei are clearly heating gas in `cooling flows'. The effectiveness and spatial distribution of the heating are controversial. We use three-dimensional simulations on adaptive grids to study the impact on a cooling flow of…
We present a scheme to extract information about plumes, a prominent coherent structure in turbulent thermal convection, from simultaneous local velocity and temperature measurements. Using this scheme, we study the temperature dependence…