The heavily polluted atmosphere of the DAZ white dwarf GALEX J193156.8+011745

TL;DR

This paper reports the discovery and detailed analysis of a heavily polluted white dwarf star, revealing ongoing accretion of planetary debris through spectral signatures and infrared excess.

Contribution

It presents the first detailed abundance analysis of GALEX J193156.8+011745, a newly identified polluted white dwarf, highlighting ongoing accretion processes.

Findings

Super-solar silicon and magnesium abundances detected

Infrared excess suggests presence of accretion source

Oxygen, calcium, and iron near solar abundances

Abstract

We report on the discovery of a new heavily polluted white dwarf. The DAZ white dwarf GALEX J193156.8+011745 was identified in a joint GALEX/GSC survey of ultraviolet-excess objects. Optical spectra obtained at ESO NTT show strong absorption lines of magnesium and silicon and a detailed abundance analysis based on VLT-Kueyen UVES spectra reveal super-solar abundances of silicon and magnesium, and near-solar abundances of oxygen, calcium, and iron. The overall abundance pattern bears the signature of ongoing accretion onto the white dwarf atmosphere. The infrared spectral energy distribution shows an excess in the H and K bands likely associated with the accretion source.