Heavy Element Abundance Patterns in Hot White Dwarfs from a Survey of the FUSE Archive

TL;DR

This study systematically measures heavy element abundances in 89 hot white dwarfs from the FUSE archive, revealing diverse compositions and potential planetary debris accretion signatures across a broad temperature range.

Contribution

It provides the largest sample to date for abundance analysis in hot white dwarfs, using advanced non-LTE models to identify peculiar stars and assess planetary debris accretion.

Findings

Wide range of heavy element abundances observed.

Some stars show no detectable heavy elements.

Potential evidence of planetary debris accretion in certain stars.

Abstract

We present a series of systematic abundance measurements for 89 hot DA white dwarfs drawn from the FUSE observation archive. These stars span the temperature range ~ 20000-70000K, and form the largest sample to-date, exceeding our earlier study, based mainly on IUE and HST data, by a factor three. Using the heavy element blanketed non-LTE stellar atmosphere calculations from this previous work, we are able to measure the abundances of carbon, silicon, phosphorus and sulphur and examine how they change as the stars cool. We are able to establish the broad range of abundances seen in a given temperature range and establish the incidence of stars which, like HZ43, appear to (surprisingly) be completely devoid of any material other than H in their atmospheres. As a result we can begin to identify stars with peculiar abundances in this temperature range and determine whether or not these objects might be accreting planetary debris, as has been inferred for many cooler objects.