Results 1 to 10 of about 34,048 (260)

Helioseismic inference of the solar radiative opacity

Nature Communications
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.
Gaël Buldgen, Jean-Christophe Pain, Philippe Cossé, Christophe Blancard, Franck Gilleron, Anil K. Pradhan, Christopher J. Fontes, James Colgan, Arlette Noels, Jørgen Christensen-Dalsgaard, Morgan Deal, Sergey V. Ayukov, Vladimir A. Baturin, Anna V. Oreshina, Richard Scuflaire, Charly Pinçon, Yveline Lebreton, Thierry Corbard, Patrick Eggenberger, Peter Hakel, David P. Kilcrease   +20 more
doaj   +7 more sources

Helioseismic Tests of Radiative Opacities. [PDF]

AIP Conference Proceedings, 2002
During the past fifteen years, thousands of solar acoustic oscillation modes have been measured to remarkable precision, in many cases to within 0.01%. These frequencies have been used to infer the interior structure of the sun and test the physical input to solar models. Here we summarize the procedures, input physics and assumptions for calculating a
J. A. Guzik, C. Neuforge, J. J. Keady, N. H. Magee, Paul A. Bradley   +4 more
  +6 more sources

Medium-induced radiative kernel with the Improved Opacity Expansion [PDF]

Journal of High Energy Physics, 2021
We calculate the fully differential medium-induced radiative spectrum at next-to-leading order (NLO) accuracy within the Improved Opacity Expansion (IOE) framework.
João Barata, Yacine Mehtar-Tani, Alba Soto-Ontoso, Konrad Tywoniuk   +3 more
doaj   +6 more sources

On radiative opacities of dense plasmas

Physica B: Condensed Matter, 1996
Abstract Besides advanced atomic data, the strong coupling effects are the key-stones for true radiative opacities and for the proper description of energy transport in dense matter. These opacities, which are sensitive to the ‘windows’ in absorption spectra, are discussed briefly in terms of strongly coupled plasmas (SCP) dielectric functions.
Yu. K. Kurilenkov, L. G. D’yachkov, M. Skowronek, Y. Vitel, Hauke Horn   +4 more
openalex   +3 more sources

Opacities for the solar radiative interior

The Astrophysical Journal, 1991
Opacities for the solar radiative interior are computed and compared to previous calculations. A significant enhancement of the Rosseland mean opacity near the bottom of the convection zone is reported when compared to the Los Alamos Astrophysical Opacity Library. The discrepancy is attributed mainly to the equation of state.
Carlos A. Iglesias, F. J. Rogers
openalex   +3 more sources

Effects of opacity temperature dependence on radiatively accelerated clouds [PDF]

Monthly Notices of the Royal Astronomical Society, 2020
ABSTRACT We study how different opacity–temperature scalings affect the dynamical evolution of irradiated gas clouds using time-dependent radiation-hydrodynamics simulations. When clouds are optically thick, the bright side heats up and expands, accelerating the cloud via the rocket effect. Clouds that become more optically thick as they
Sergei Dyda, Daniel Proga, C. S. Reynolds   +2 more
openalex   +3 more sources

Radiative Transfer with Opacity Distribution Functions: Application to Narrowband Filters [PDF]

The Astrophysical Journal Supplement Series, 2021
Abstract Modeling of stellar radiative intensities in various spectral passbands plays an important role in stellar physics. At the same time, direct calculation of the high-resolution spectrum and then integration of it over the given spectral passband is computationally demanding due to the vast number of atomic and molecular lines ...
L. S. Anusha, A. I. Shapiro, Veronika Witzke, Miha Černetič, S. K. Solanki, L. Gizon   +5 more
openalex   +7 more sources

Stellar Pulsation and Evolution: A Combined Theoretical Renewal and Updated Models (SPECTRUM). I. Updating Radiative Opacities for Pulsation Models of Classical Cepheid and RR-Lyrae [PDF]

The Astrophysical Journal
Pulsating stars are universally recognized as precise distance indicators and tracers of stellar populations. Their variability, combined with well-defined relationships between pulsation properties and intrinsic evolutionary parameters such as ...
Giulia De Somma, Marcella Marconi, Santi Cassisi, Roberto Molinaro   +3 more
doaj   +3 more sources

Opacity Sampling in Radiative Acceleration Calculations [PDF]

The Astrophysical Journal, 2000
The accuracy requirements on atomic data for the calculation of stellar evolution with atomic diffusion are determined. In particular, the density of frequency grids needed for precise radiative acceleration (grad) calculations via the sampling method are presented.
F. Leblanc, G. Michaud, J. Richer
openalex   +4 more sources

Updated Opacity Project radiative accelerations [PDF]

Monthly Notices of the Royal Astronomical Society, 2007
Updated data for the calculation of radiative accelerations, grad, referred to as OP 2005, have been made generally available on the Web. They differ from the earlier 1997 OP data mainly in the inclusion of contributions from inner-shell processes. The frequency resolution used for OP 2005 is shown to be satisfactory except for extreme cases of low ...
M. J. Seaton
openalex   +3 more sources