A study of the Lyman-$\alpha$ line profile in DBA white dwarfs

TL;DR

This paper investigates the Lyman-alpha line profile in DBA white dwarfs to resolve discrepancies in hydrogen abundance measurements from optical and UV spectra, offering improved analysis methods.

Contribution

It introduces a detailed theoretical model of the Lyman-alpha line profile considering temperature and hydrogen levels, addressing previous measurement inconsistencies.

Findings

Identified a potential solution to hydrogen abundance discrepancies.

Achieved improved consistency between optical and UV spectral analyses.

Provided a refined model for Lyman-alpha line profiles in DBA white dwarfs.

Abstract

The hydrogen abundances in DBA white dwarfs determined from optical or UV spectra have been reported to differ significantly in some studies. We revisit this problem using our own model atmospheres and synthetic spectra, and present a theoretical investigation of the Lyman-$\alpha$ line profile as a function of effective temperature and hydrogen abundance. We identify one possible solution to this discrepancy and show considerable improvement from a detailed analysis of optical and UV spectra of DBA stars.