Challenges in Solar and Stellar Model Physics

TL;DR

This paper reviews current challenges in modeling stars, emphasizing uncertainties in physical inputs, and discusses how asteroseismology data from space missions can help address these issues.

Contribution

It highlights the unresolved problems in stellar physics, including the solar abundance problem and pulsation frequency mismatches, and explores how observational data can improve models.

Findings

Modified electron screening affects solar models

Asteroseismology constrains physical processes in stars

Discrepancies in delta Sct star frequency predictions

Abstract

We are reaching relative maturity and standardization in one-dimensional single-star stellar evolution and pulsation modeling, and are making advances in binary and 2D and 3D models. However, many physical inputs are still uncertain or neglected in models of the Sun and of other stars. Thanks to the the Kepler, CoRoT, and MOST spacecraft, for example, as well as to ground-based networks, we now have pulsation data for stars that are of comparable quality to that for the Sun to constrain models and test physical assumptions. Here I will focus on main sequence (core H-burning) or slightly post-main sequence (shell H-burning) stellar models, and some of the unsolved problems for these stars. I will revisit the solar abundance problem, and show the effects of modified electron screening, dark matter, and early mass loss on solar models. I will discuss the gamma Dor/ delta Sct hybrid stars, the mismatch between predicted and observed frequencies for delta Sct stars, and how seismology of stars more massive than the Sun, e.g. the brightest Kepler target theta Cyg, could help us constrain physical processes such as diffusive settling, test pulsation driving mechanisms, and provide clues to the solar abundance problem.