Asteroseismology of white dwarfs in the 2040s

TL;DR

White dwarf asteroseismology offers insights into their internal structure and evolution, but challenges in mode excitation understanding and mass determination persist, which large-scale surveys aim to address.

Contribution

This paper reviews recent advances and remaining challenges in white dwarf asteroseismology, emphasizing future survey prospects for improved internal structure insights.

Findings

Space missions have provided high-precision photometry for white dwarfs.

Discrepancies exist between different methods of mass determination.

Large-scale surveys will significantly enhance white dwarf pulsation data.

Abstract

White dwarfs, the final evolutionary stage of the vast majority of stars, serve as critical tools for cosmochronology, studies of planetary system evolution, and laboratories for non-standard physics, including exotic cooling channels and weakly interacting particles, as well as crystallization processes. Beyond surface properties accessible via spectroscopy and model atmospheres, global pulsations exhibited by white dwarfs during various evolutionary phases provide a direct window into their deep interiors. Asteroseismology, the comparison of observed pulsation periods with theoretical models, enables us to infer internal chemical stratification, total mass, rotation profiles, and magnetic field strengths. Despite major advances from space missions providing uninterrupted, high-precision photometry, key challenges remain: many predicted pulsators remain quiet, while others oscillate outside theoretical instability strips, highlighting gaps in our understanding of mode excitation, diffusion, and convective mixing. Determining the masses of white dwarfs, particularly for massive and hydrogen-deficient stars, remains uncertain, with discrepancies between spectroscopic, asteroseismic, astrometric, and photometric methods. In the coming decades, large-scale surveys combining high-precision space-based photometry with coordinated ground-based spectroscopic follow-up will dramatically increase both the number and quality of pulsating white dwarf observations.