Hydrogen-Atmosphere White Dwarfs Are Less Likely To Be Found with Wide-Binary Companions

TL;DR

This study estimates the frequency of white dwarfs in wide binary systems, revealing hydrogen-atmosphere white dwarfs are less likely to have wide companions compared to other types, with specific binary fractions quantified.

Contribution

It provides the first detailed comparison of wide-binary fractions among different white dwarf atmospheric types using spectroscopic classifications.

Findings

Hydrogen-atmosphere white dwarfs have a ~5% wide-binary fraction.

Binary fraction for DA white dwarfs is 6.3%.

Binary fraction for non-DA white dwarfs is 8.0%.

Abstract

The fraction of white dwarfs found in wide binaries is estimated by cross referencing a catalogue of wide binaries with catalogues photometrically determined white-dwarf candidates and spectroscopically confirmed white dwarf stars. The wide-binary fraction of white dwarfs with hydrogen-dominated atmospheres is about 5%, but the fraction of white dwarfs with helium or carbon-dominated atmospheres is significantly larger. Using spectroscopic classifications, the binary fraction of DA white dwarfs is determined to be $0.063\pm0.002$ and for non-DA white dwarfs is larger at $0.080\pm0.004$.