Related papers: Line broadening and the solar opacity problem
The computation of radiative opacity or emissivity of hot dense matter is a challenging task. It requires accounting for an immense number of energy levels and lines across various excitation and ionization states. Whether in local…
We implemented non-solar-scaled opacities in a simultaneous derivation of fundamental parameters and abundances. We carried out a high-precision stellar parameters and abundance determination by applying non-solar-scaled opacities and model…
The Sun and $\alpha$ Cen A and B are the nearest stars to us. Despite the general agreement between their models and seismic and non-seismic constraints, there are serious problems pertaining to their interior. The good agreement between…
Nowadays, several opacity codes are able to provide data for stellar structure models, but the computed opacities may show significant differences. In this work, we present state-of-the-art precise spectral opacity calculations, illustrated…
Spectral lines of heavy atomic elements in the ejecta of supernovae and neutron star mergers can have important contribution to the opacity of the ejecta matter even when the abundance of the elements is very small. Under favorable…
The revision of the standard Los Alamos opacities in the 1980-1990s by a group from the Lawrence Livermore National Laboratory (OPAL) and the Opacity Project (OP) consortium was an early example of collaborative big-data science, leading to…
Despite recent major advances, the opacity remains a source of substantial uncertainty in the calculation of solar models, and hence of solar oscillation frequencies. Hence it is of substantial interest to investigate the sensitivity of…
Context. Realistic 3D time-dependent simulations of stellar near-surface convection employ the opacity binning method for efficient and accurate computation of the radiative energy exchange. The method provides several orders of magnitude…
Oscillation properties are usually measured by fitting symmetric Lorentzian profiles to the power spectra of Sun-like stars. However the line profiles of solar oscillations have been observed to be asymmetrical for the Sun. The physical…
The effects of background line opacity (line-blocking) in statistical equilibrium calculations for Fe in late-type stellar atmospheres have been investigated using an extensive and up-to-date model atom with radiative data primarily from…
We present significant improvements of our approach in constructing detailed atmospheric models and synthetic spectra for hot luminous stars: 1. A sophisticated and consistent description of line blocking and blanketing. Our solution…
In order to complete data on Stark broadening parameters for Ar I line in the visible spectrum, we determined Stark widths and shifts due to electron, proton, and ionized helium impacts, for nine lines (4191.0, 4259.4, 5912.1, 6043.2,…
We show that the line broadening in quiescent solar prominences is mainly due to non-thermal velocities. We have simultaneously observed a wide range of optically thin lines in quiescent prominences, selected for bright and narrow Mg\,b…
Calculations of spectral darkening and visibility functions for the brightness oscillations of the Sun resulting from global solar oscillations are presented. This has been done for a broad range of the visible and infrared continuum…
Monte Carlo calculations of the O Kalpha line fluoresced by coronal X-rays and emitted just above the temperature minimum region of the solar atmosphere have been employed to investigate the use of this feature as an abundance diagnostic.…
The Sun is the most studied of all stars, and thus constitutes a benchmark for stellar models. However, our vision of the Sun is still incomplete, as illustrated by the current debate on its chemical composition. The problem reaches far…
Recent revisions of the determination of the solar composition have resulted in solar models in marked disagreement with helioseismic inferences. The effect of the composition change on the model is largely caused by the change in the…
The study of Stark broadening of neutral helium lines, despite significant advances over recent decades, has not led to updated large grids of helium line profiles relevant to the spectroscopic study of helium-rich stars. While the…
Context. Radiation-driven mass loss is key to our understanding of massive-star evolution. However, for low-luminosity O-type stars there are big discrepancies between theoretically predicted and empirically derived mass-loss rates (called…
In accelerating and supersonic media, the interaction of photons with spectral lines can be of ultimate importance. However, fully accounting for such line forces currently can only be done by specialised codes in 1-D steady-state flows.…