Red supergiant star studies with CO5BOLD and Optim3D

TL;DR

This paper reviews recent advances in 3D radiative-hydrodynamics simulations of red supergiant stars, highlighting improvements and ongoing challenges in matching observational data and addressing temperature scale controversies.

Contribution

It demonstrates the application of CO5BOLD and Optim3D simulations to better understand red supergiants and discusses the impact of non-grey radiation treatment on observational agreement.

Findings

Non-grey radiation treatment improves simulation-observation match.

Simulations still struggle with line depth and width reproduction.

Long-term simulations provide valuable insights into stellar behavior.

Abstract

We describe recent work focused towards a better understanding of red supergiant stars using 3D radiative-hydrodynamics (RHD) simulations with CO5BOLD. A small number of simulations now exist that span up to seven years of stellar time, at various numerical resolutions. Our discussion concentrates on interferometric and spectroscopic observations. We point out a number of problems, in particular the line depth and line width that are not well reproduced by simulations. The most recent introduction of a non-grey treatment of the radiation field dramatically improved the match with observations, without solving all difficulties. We also review the newly revived effective temperature scale controversy, and argue that it will only be solved using 3D RHD models.