Oxygen opacity experiments for stellar interiors at Z

Much of our knowledge of the universe stems from our understanding of the Sun. However, ongoing disagreement between solar models and helioseismic measurements of the interior structure of the Sun raises concerns about the accuracy of stellar models. One hypothesis that could resolve this discrepancy is if the opacities of matter at solar interior conditions are higher than models predict. Experiments on the Z Machine have been investigating this by measuring the opacity of iron and oxygen at conditions near the solar convection zone base (CZB). From these, iron has shown a discrepancy between experiment and models at these conditions that has yet to be resolved. This talk will focus on the progress of the oxygen opacity experiments. Oxygen is the largest contributor to the opacity at the solar CZB and no experimental benchmark in this regime exists to date. We will discuss the methods for measuring the opacity and for characterizing the plasma and what has been found.