http://arxiv.org/abs/1603.01153
The calculation of line widths constitutes a theoretical as well as a computational challenge 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 nearby the convection zone boundary (CZB) of the sun, indicate a large discrepancy in the K-shell line widths between several atomic codes and the Opacity-Project. In this work, the atomic code STAR is used to study the sensitivity of solar opacities to line-broadening. Atomic spectra of several elements are analyzed and compared within the solar interior. Variations in the solar opacity profile due to changes in the Stark widths are shown to be significant and to result mainly due to K-shell lines. In light of the solar opacity problem, the results are compared with the required opacity variations of the present day sun, as imposed by helioseismic and neutrino observations. It is shown that an increase of the line widths results in a smooth increase of the solar opacity profile, ranging from about 15% nearby the CZB to about 2% at the solar core. This systematic variation is much larger than the discrepancy between different atomic codes and significantly reduces the missing opacity nearby the CZB, required by observable constraints of present day sun. It also highlights 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 state of the art atomic codes.
M. Krief, A. Feigel and D. Gazit
Fri, 4 Mar 16
35/61
Comments: Submitted to ApJL
You must be logged in to post a comment.