Stars with Unusual Compositions: Carbon and Oxygen in Cool White Dwarf Stars

TL;DR

This paper reviews the observational signatures, physical properties, and evolution of cool white dwarf stars with unusual compositions, focusing on carbon and oxygen detection, and discusses future research challenges.

Contribution

It provides a comprehensive overview of the current understanding of carbon and oxygen in cool white dwarf stars and highlights key challenges for future studies.

Findings

Detailed characterization of DQ, DBQ, and Hot DQ white dwarfs

Summary of observational signatures and physical properties

Identification of main challenges for future research

Abstract

I present a broad historical review on cool white dwarf stars with carbon and/or oxygen detected at the photosphere. This book chapter covers the observational signatures, physical properties, and evolution of DQ, DBQ and Hot DQ white dwarfs, and also present an overview of the main challenges that future investigations of these types of object should try to address.