Recent advances in the theoretical modeling of pulsating low-mass He-core white dwarfs

TL;DR

This paper reviews recent theoretical progress in modeling pulsations of low-mass helium-core white dwarfs and pre-white dwarfs, highlighting their nonadiabatic pulsation properties and potential observational signatures.

Contribution

It provides a comprehensive theoretical analysis of pulsation modes in low-mass He-core WDs and pre-WDs using fully evolutionary models, advancing understanding of their oscillation behavior.

Findings

Identification of nonradial g-mode pulsations in ELM WDs

Prediction of short-period p-mode and radial mode variations in pre-WDs

Enhanced understanding of pulsation driving mechanisms in low-mass WDs

Abstract

Many extremely low-mass (ELM) white-dwarf (WD) stars are currently being found in the field of the Milky Way. Some of these stars exhibit long-period nonradial $g$-mode pulsations, and constitute the class of ELMV pulsating WDs. In addition, several low-mass pre-WDs, which could be precursors of ELM WDs, have been observed to show short-period photometric variations likely due to nonradial $p$ modes and radial modes. They could constitute a new class of pulsating low-mass pre-WD stars, the pre-ELMV stars. Here, we present the recent results of a thorough theoretical study of the nonadiabatic pulsation properties of low-mass He-core WDs and pre-WDs on the basis of fully evolutionary models representative of these stars.