Related papers: Element Diffusion in the Solar Interior
Depending on the topology of the magnetic field and characteristics of turbulent motions, diffusion can significantly affect the distribution of elements, in particular helium, in the intracluster medium (ICM). As has been noted previously,…
Primary inversions of accurately measured solar oscillation frequencies coupled with the equations of thermal equilibrium and other input physics, enable us to infer the temperature and hydrogen abundance profiles inside the Sun. These…
Using reconstructed opacities, we construct solar models with low heavy-element abundance. Rotational mixing and enhanced diffusion of helium and heavy elements are used to reconcile the recently observed abundances with helioseismology.…
Diffusion of elements in the atmosphere and envelope of a star can drastically alter its surface composition, leading to extreme chemical peculiarities. We consider the case of hot subdwarfs, where surface helium abundances range from…
Helioseismology has shown that the chemical composition of the Sun has changed over its lifetime. The surface abundance of helium and heavy elements is believed to have decreased by up to 10% relative to their initial values. However, this…
The formation of sdBs is still puzzling, as is the chemical composition of their atmospheres. While helium and other light elements are depleted relative to solar values, heavy elements are highly enriched. Diffusion processes in the hot,…
We have evolved 10,000 solar models using 21 input parameters that are randomly drawn for each model from separate probability distributions for every parameter. We use the results of these models to determine the theoretical uncertainties…
This paper discusses low mass, metal poor stars, presenting new evolutionary computations which take into account the inward diffusion of both He and heavy elements during the H burning phase. The investigation has been extended to He…
Recent downward revision of solar heavy-element abundances using three-dimensional atmospheric model has introduced serious discrepancies between standard solar models and helioseismic inferences about solar structure. In this paper, we…
The recent downward revision of solar photospheric abundances of Oxygen and other heavy elements has resulted in serious discrepancies between solar models and solar structure as determined through helioseismology. In this work we…
We revisit the phenomenon of elements diffusion in the intergalactic medium (IGM) in clusters of galaxies. The diffusion is driven by gravity, concentration and temperature gradients. The latter cause thermal diffusion, which has been so…
The latest solar atmosphere models include non-LTE corrections and 3D hydrodynamic convection simulations. These models predict a significant reduction in the solar metal abundance, which leads to a serious conflict between helioseismic…
The interior structure of the Sun can be studied with great accuracy using observations of its oscillations, similar to seismology of the Earth. Precise agreement between helioseismological measurements and predictions of theoretical solar…
The structural stratification of a solar-type main sequence star primarily depends on its mass and chemical composition. The surface heavy element abundances of the solar-type stars are reasonably well determined using conventional…
Element diffusion is expected to occur in all kinds of stars : according to the relative effect of gravitation and radiative acceleration, they can fall or be pushed up in the atmospheres. Helium sinks in all cases, thereby creating a…
Hydrogen diffusion in metals and alloys plays an important role in the discovery of new materials for fuel cell and energy storage technology. While analytic models use hand-selected features that have clear physical ties to hydrogen…
Stellar cores may be considered as a nuclear reactor that play important role in injecting new synthesized elements in the interstellar medium Helium burning is an important stage that contribute to the synthesis of key elements such as…
The variability of helium abundance in the solar corona and the solar wind is an important signature of solar activity, solar cycle, solar wind sources, as well as coronal heating processes. Motivated by recently reported remote sensing UV…
We present results of molecular dynamics simulations of the electron system on the surface of liquid helium. The simulations are done for 1600 electrons with periodic boundary conditions. Electron scattering by capillary waves and phonons…
An improved microscopic diffusion in stars is presented considering in detail the partly ionized stages of metals. Besides,the influence of degenerate electron-gas and of the contribution of radiation to the total pressure has been…