Asteroseismic Constraints on the Models of Hot B Subdwarfs: Convective Helium-Burning Cores

TL;DR

This paper discusses how asteroseismology of hot B subdwarfs provides insights into their convective helium-burning cores, challenging existing stellar models and emphasizing the need for improved convection treatments based on 3D simulations.

Contribution

It highlights the importance of asteroseismology in constraining stellar core models and advocates for integrating 3D convection insights into 1D stellar evolution models.

Findings

Asteroseismology reveals detailed core structure of sdB stars.

Current convective mixing models are inconsistent with observations.

3D simulations offer promising guidance for improved convection modeling.

Abstract

Asteroseismology of non-radial pulsations in Hot B Subdwarfs (sdB stars) offers a unique view into the interior of core-helium-burning stars. Ground-based and space-borne high precision light curves allow for the analysis of pressure and gravity mode pulsations to probe the structure of sdB stars deep into the convective core. As such asteroseismological analysis provides an excellent opportunity to test our understanding of stellar evolution. In light of the newest constraints from asteroseismology of sdB and red clump stars, standard approaches of convective mixing in 1D stellar evolution models are called into question. The problem lies in the current treatment of overshooting and the entrainment at the convective boundary. Unfortunately no consistent algorithm of convective mixing exists to solve the problem, introducing uncertainties to the estimates of stellar ages. Three dimensional simulations of stellar convection show the natural development of an overshooting region and a boundary layer. In search for a consistent prescription of convection in one dimensional stellar evolution models, guidance from three dimensional simulations and asteroseismological results is indispensable.