Signatures of convection in the atmospheres of cool evolved stars

TL;DR

This paper discusses the importance of convection in the atmospheres of cool evolved stars, highlighting the use of advanced 3D simulations to understand their complex convective processes and their impact on stellar feedback and supernova emissions.

Contribution

It introduces two state-of-the-art 3D radiation-hydrodynamics codes, CO5BOLD and Athena++, for studying stellar convection in evolved cool stars.

Findings

Convection in these stars transitions to a global scale due to high luminosity.

The codes enable detailed investigation of dynamic convective processes.

They are used to model emissions during supernova shock breakouts.

Abstract

Evolved cool stars of various masses are major cosmic engines, delivering substantial mechanical and radiative feedback to the interstellar medium through strong stellar winds and supernova ejecta. These stars play a pivotal role in enriching the interstellar medium with vital chemical elements that constitute the essential building blocks for forming subsequent generations of stars, planets, and potentially even life. Within the complex tapestry of processes occurring in the atmospheres of these cool and luminous stars, convection takes center stage. Convection is a non-local, complex phenomenon marked by non-linear interactions across diverse length scales within a multi-dimensional framework. For these particular stars, characterized by their considerable luminosities and extensive scale heights, convection transitions to a global scale. This transition is facilitated by transmitting radiative energy through the non-uniform outer layers of their atmospheres. To fully understand this phenomenon, the application of global comprehensive 3D radiation-hydrodynamics simulations of stellar convection is of paramount importance. We present two state-of-the-art numerical codes: CO5BOLD and Athena++. Furthermore, we provide a view on their applications as: pivotal roles in enabling a comprehensive investigation into the dynamic processes linked to convection; and critical tools for accurately modeling the emissions produced during shock breakouts in Type II-P Supernovae.