Line broadening and the solar opacity problem

Abstract

The calculation of line widths constitutes theoretical and computational challenges in the calculation of opacities of hot dense plasmas. Opacity models use line broadening approximations that are untested at stellar interior conditions. Moreover, calculations of atomic spectra of the sun, indicate a large discrepancy in the K-shell line widths between several atomic codes and the OP. In this work, the atomic code STAR is used to study the sensitivity of solar opacities to line-broadening. Variations in the solar opacity profile, due to an increase of the Stark widths resulting from discrepancies with OP, are compared, in light of the solar opacity problem, with the required opacity variations of the present day sun, as imposed by helioseismic and neutrino observations. The resulting variation profile, is much larger than the discrepancy between different atomic codes, agrees qualitatively with the missing opacity profile, recovers about half of the missing opacity nearby the convection boundary and has a little effect in the internal regions. Since it is hard to estimate quantitatively the uncertainty in the Stark widths, we show that an increase of all line widths by a factor of about 100 recovers quantitatively the missing opacity. These results emphasize the possibility that photoexcitation processes are not modeled properly, and more specifically, highlight the need for a better theoretical characterization of the line broadening phenomena at stellar interior conditions and of the uncertainty due to the way it is implemented by atomic codes.

Version accepted for publication in ApJ

References in corpus (19)

• The chemical composition of the Sun
• Solar Chemical Abundances Determined with a CO5BOLD 3D Model Atmosphere
• Up-dated opacities from the Opacity Project
• New Solar Composition: The Problem With Solar Models Revisited
• Constraining solar abundances using helioseismology
• The elemental composition of the Sun II. The iron group elements Sc to Ni
• The elemental composition of the Sun I. The intermediate mass elements Na to Ca
• A New Generation of Los Alamos Opacity Tables
• The elemental composition of the Sun III. The heavy elements Cu to Th
• On the opacity change required to compensate for the revised solar composition
• The chemical composition of the Sun from helioseismic and solar neutrino data
• Constraints on the opacity profile of the sun from helioseismic observables and solar neutrino flux measurements
• Solar opacity calculations using the super-transition-array method
• Highly Excited Core Resonances in Photoionization of Fe XVII : Implications for Plasma Opacities
• First solar models with OPAS opacity tables
• Linear Solar Models
• Average Atom Model based on Quantum Hyper-Netted Chain Method
• Effect of third- and fourth-order moments on the modeling of Unresolved Transition Arrays
• IPOPv2 online service for the generation of opacity tables

Cited by in corpus (15)

• A new Generation of Standard Solar Models
• On Variations Of Pre-Supernova Model Properties
• The Future of Solar Neutrinos
• Implications of solar wind measurements for solar models and composition
• Solar models in light of new high metallicity measurements from solar wind data
• Solar fusion III: New data and theory for hydrogen-burning stars
• Plasma opacity calculations using the Starrett and Saumon average-atom model with ion correlations
• An Expanded Set of Los Alamos OPLIB Tables in MESA: Type-1 Rosseland-mean Opacities and Solar Models
• Helioseismic and Neutrino Data Driven Reconstruction of Solar Properties
• The effect of hyperfine splitting on Stark broadening for three blue-green Cu I lines in laser-induced plasma
• The number of populated electronic configurations in a hot dense plasma
• Charge State Distributions in Dense Plasmas
• Computation of atomic astrophysical opacities
• Progress in global helioseismology: a new light on the solar modelling problem and its implications for solar-like stars
• Global Helioseismology