Might Carbon-Atmosphere White Dwarfs Harbour a New Type of Pulsating Star?

TL;DR

This paper explores the potential for a new type of white dwarf with carbon atmospheres to exhibit pulsations, based on theoretical models suggesting they could be unstable against gravity modes, similar to other pulsating white dwarfs.

Contribution

It introduces the idea that carbon-atmosphere white dwarfs may pulsate, expanding the class of known pulsating white dwarfs and providing a new avenue for asteroseismological studies.

Findings

Some carbon-atmosphere white dwarfs are predicted to be pulsationally unstable.

Models show similarities between their ionized layers and those in known pulsating white dwarfs.

Further observational searches are needed to confirm pulsations in these stars.

Abstract

In the light of the recent and unexpected discovery of a brand new type of white dwarfs, those with carbon-dominated atmospheres, we examine the asteroseismological potential of such stars. The motivation behind this is based on the observation that past models of carbon-atmosphere white dwarfs have partially ionized outer layers that bear strong resemblance with those responsible for mode excitation in models of pulsating DB (helium-atmosphere) and pulsating DA (hydrogen-atmosphere) white dwarfs. Our exciting main result is that, given the right location in parameter space, some carbon-atmosphere white dwarfs are predicted to show pulsational instability against gravity modes. We are eagerly waiting the results of observational searches for luminosity variations in these stars.