Can mass loss and overshooting prevent the excitation of g-modes in blue supergiants?

TL;DR

This paper investigates how mass loss and overshooting in blue supergiants influence the development of the intermediate convective zone and the excitation of g-modes, revealing that these phenomena can suppress g-mode excitation.

Contribution

It introduces a numerical method to select reflected g-modes and demonstrates that significant mass loss and overshooting hinder g-mode excitation in supergiants.

Findings

Mass loss and overshooting reduce the extent of the ICZ.

These phenomena are unfavorable for g-mode excitation.

The method effectively identifies potentially excited modes.

Abstract

Thanks to their past history on the main sequence phase, supergiant massive stars develop a convective shell around the helium core. This intermediate convective zone (ICZ) plays an essential role in governing which g-modes are excited. Indeed a strong radiative damping occurs in the high density radiative core but the ICZ acts as a barrier preventing the propagation of some g-modes into the core. These g-modes can thus be excited in supergiant stars by the kappa-mechanism in the superficial layers due to the opacity bump of iron, at log T=5.2. However massive stars are submitted to various complex phenomena such as rotation, magnetic fields, semiconvection, mass loss, overshooting. Each of these phenomena exerts a significant effect on the evolution and some of them could prevent the onset of the convective zone. We develop a numerical method which allows us to select the reflected, thus the potentially excited, modes only. We study different cases in order to show that mass loss and overshooting, in a large enough amount, reduce the extent of the ICZ and are unfavourable to the excitation of g-modes.