Oxygen opacity experiments to advance our understanding of stellar interiors

The “solar problem” was revealed when a change in measured solar abundances produced disagreement between solar model predictions and helioseismic measurements. The discrepancy could be resolved if the opacity of materials at conditions near the convection zone base (CZB) is higher than predicted by models. Oxygen and iron are among the most important contributors to opacity near the solar CZB. Previous experiments with iron showed notable differences between theory and experiment. To further investigate this topic, we have begun using the previously developed opacity platforms at Z and NIF to study oxygen opacity at the relevant conditions. Measurements of oxygen opacity have been carried out using SiO₂ and/or MgO samples at each facility. In this talk, we will discuss the experimental platforms, the methods used for diagnosing experiment conditions, as well as some of the preliminary results from each platform.