Cairo University

MTPR Journal

 

STUDY OF OUR STAR THE SUN

& doi: https://doi.org/10.19138/MTPR/(14)188-199
Sultana N. Nahar

Our sun is studied extensively as it is the standard for a typical star. However, knowledge about the Sun still has large discrepancies. Recent determination of abundances of common elements such as carbon, nitrogen, oxygen, etc. are up to 30-50\% lower than the current standard values. Much of these discrepancies could be reduced if a fundamental quantity, the opacity of solar plasma, is revised upwards. Propagating radiation in plasmas is absorbed and emitted by the constituent elements that constitute the opacity effect. Recently measured opacities at the Sandia National Laboratory on the Z-pinch nuclear fusion device, under stellar interior conditions created on the Earth for the first time, are 30-400\% higher than predictions for the most crucial element Iron. Theoretically, new large-scale calculations under the Iron Opacity Project reveal the existence of extensive and dominant resonant features in high energy photoionization. I will illustrate these and discuss how their inclusion should provide more accurate opacities, and close the gap between observed and predicted opacities and elemental abundances in the Sun. This work was supported partially by the U.S. National Science Foundation and the Department of Energy.