Toward a systematic cartography of the chemical stratification inside white dwarfs from deep asteroseismic probing of ZZ Ceti stars

TL;DR

This paper demonstrates how deep asteroseismic analysis of ZZ Ceti stars can systematically map the chemical stratification inside white dwarfs, providing new insights into their core structure and stellar evolution history.

Contribution

It introduces a method to fully characterize the chemical stratification of white dwarfs using asteroseismology, linking pulsation data to internal composition profiles.

Findings

Successful mapping of chemical stratification in white dwarfs.

Constraints on the C/O core structure derived from pulsation data.

Establishment of a systematic approach for white dwarf internal property exploration.

Abstract

DA-type white dwarfs account for 80% of all white dwarfs and represent, for most of them, the ultimate outcome of the typical evolution of low-to-intermediate mass stars. Their internal chemical stratification is strongly marked by passed, often uncertain, stellar evolution processes that occurred during the helium (core and shell) burning phases, i.e., from the horizontal branch through AGB and post-AGB stages. Pulsating white dwarfs, in particular the "cool" DA-type ZZ Ceti variables, offer an outstanding opportunity to dig into these stars by fully exploiting their asteroseismic potential. With our most recent tools dedicated to that purpose, we show that a complete cartography of the stratification of the main constituents of a white dwarf can be inferred, leading in particular to strong constraints on the C/O core structure produced by the processes mentioned above. This opens up the way toward a systematic exploration of white-dwarf internal properties.