Title: Ingredients for better stellar models
Speaker: Regner Trampedach
Affiliation: Space Science Institute
Time: Monday 14th October 2024, 14:00 to 15:00
Location: 101190 Å
Abstract: Our stellar models can obviously only be as good as the physics we put into them. One sign that improvements are needed, comes from the decades old "Solar abundance problem" where the highest quality spectroscopic abundance analysis is at odds with the highest quality helioseismic analysis - by some 15 standard deviations! I'll present my work on building an equation of state (EOS) that is both accurate and complete (all relevant physics included), from the core to the atmosphere of most stars, from pre-main sequence to red giants, to white dwarfs. This EOS will be used as a basis for a new opacity calculation, with new absorption coefficients computed with the (relativistic) R-matrix method, abandoning the usual distorted wave approximation. Crucially, these photoionization cross-sections will be broadened by the plasma environment, just as normal spectral lines. These and other improvements have a realistic potential to solve the Solar abundance problem, and will affect stellar modeling in general, and hence, our understanding of the stars we observe.