Driving and damping mechanisms in hybrid pressure-gravity modes pulsators

TL;DR

This paper investigates the energetic mechanisms behind hybrid pressure-gravity pulsations in stars, highlighting the roles of element composition and propagation regions in mode stability, with implications for different types of pulsators.

Contribution

It reveals the influence of propagation and evanescent regions on mode stability and extends understanding of hybrid pulsator behavior beyond previous models.

Findings

Propagation region characteristics affect mode stability.

Heavy element mixture influences driving mechanisms.

Stable frequency gap depends on propagation properties.

Abstract

We study the energetic aspects of hybrid pressure-gravity modes pulsations. The case of hybrid beta Cephei-SPB pulsators is considered with special attention. In addition to the already known sensitivity of the driving mechanism to the heavy elements mixture (mainly the iron abundance), we show that the characteristics of the propagation and evanescent regions play also a major role, determining the extension of the stable gap in the frequency domain between the unstable low order pressure and high order gravity modes. Finally, we consider the case of hybrid delta Sct-gamma Dor pulsators.