Testing the core overshooting mixing described by the turbulent convection model on the eclipsing binary star HY Vir

TL;DR

This paper tests a turbulent convection model's core overshooting mixing on the eclipsing binary star HY Vir, finding that the model's parameters are applicable and that incomplete mixing affects hydrogen profiles during stellar evolution.

Contribution

It applies the turbulent convection model to stellar overshooting outside the core and calibrates it using observations of HY Vir, demonstrating its broader applicability.

Findings

TCM parameters suitable for HY Vir

Incomplete mixing causes continuous hydrogen profiles

Overshooting region length increases over evolution

Abstract

Helioseismic investigation has suggested to apply the turbulent convection models (TCMs) to the convective overshooting. Using the turbulent velocity in the overshooting region determined by the TCM, one can deal with the overshooting mixing as a diffusion process, which leads to incomplete mixing. It has been found that this treatment can improve the solar sound speed and the Li depletion in open clusters. In order to investigate whether the TCM can be applied to the overshooting mixing outside the stellar convective core, new observations of the eclipsing binary star HY Vir are adopted to calibrate the overshooting mixing parameter. The main conclusions are as follows: (i) the TCM parameters and the overshooting mixing parameter in the solar case are also suitable for the eclipsing binary system HY Vir; (ii) the incomplete mixing results in a continuous profile of the hydrogen abundance; (iii) the e-folding length of the region, in which the hydrogen abundance changes due to the overshooting mixing, increases during the stellar evolution.