A subtle IR excess associated with a young White Dwarf in the Edinburgh-Cape Blue Object Survey

TL;DR

This study reports a subtle infrared excess around a young white dwarf, indicating the presence of a debris disk and active metal accretion, with implications for understanding white dwarf pollution and disk geometries.

Contribution

It introduces the possibility of elliptical debris disks to explain subtle IR excesses, expanding the interpretation of white dwarf circumstellar environments.

Findings

Infrared excess consistent with a debris disk

White dwarf shows atmospheric metal pollution

Elliptical disk models broaden acceptable disk parameters

Abstract

We report the discovery of a subtle infrared excess associated with the young white dwarf EC\,05365--4749 at 3.35 and 4.6\,$\mu$m. Follow-up spectroscopic observations are consistent with a hydrogen atmosphere white dwarf of effective temperature 22\,800\,K and log [\emph{g} (\,cm\,s$^{-2}$) ] = 8.19. High resolution spectroscopy reveals atmospheric metal pollution with logarithmic abundances of [Mg/H] = --5.36 and [Ca/H] = --5.75, confirming the white dwarf is actively accreting from a metal-rich source with an intriguing abundance pattern. We find that the infrared excess is well modeled by a flat, opaque debris disk, though disk parameters are not well constrained by the small number of infrared excess points. We further demonstrate that relaxing the assumption of a circular dusty debris disk to include elliptical disks expands the widths of acceptable disks, adding an alternative interpretation to the subtle infrared excesses commonly observed around young white dwarfs.