The WIRED Survey. IV. New Dust Disks from the McCook & Sion White Dwarf Catalog

TL;DR

This study uses infrared survey data to identify new white dwarf stars with circumstellar dust disks, expanding the understanding of dust disk properties and their prevalence among white dwarfs.

Contribution

The paper reports the discovery of seven new white dwarf dust disk candidates using infrared data, and compares their properties with previously known disks, highlighting a broader parameter space.

Findings

Seven new white dwarf dust disk candidates identified.

Current census of white dwarf dust disks may be nearly complete at certain wavelengths.

Discovered disks tend to be cooler, narrower, and contain fewer grains.

Abstract

We have compiled photometric data from the Wide-field Infrared Survey Explorer All Sky Survey and other archival sources for the more than 2200 objects in the original McCook & Sion Catalog of Spectroscopically Identified White Dwarfs. We applied color-selection criteria to identify 28 targets whose infrared spectral energy distributions depart from the expectation for the white dwarf photosphere alone. Seven of these are previously known white dwarfs with circumstellar dust disks, five are known central stars of planetary nebulae, and six were excluded for being known binaries or having possible contamination of their infrared photometry. We fit white dwarf models to the spectral energy distributions of the remaining ten targets, and find seven new candidates with infrared excess suggesting the presence of a circumstellar dust disk. We compare the model dust disk properties for these new candidates with a comprehensive compilation of previously published parameters for known white dwarfs with dust disks. It is possible that the current census of white dwarfs with dust disks that produce an excess detectable at K-band and shorter wavelengths is close to complete for the entire sample of known WDs to the detection limits of existing near-IR all-sky surveys. The white dwarf dust disk candidates now being found using longer wavelength infrared data are drawn from a previously underrepresented region of parameter space, in which the dust disks are overall cooler, narrower in radial extent, and/or contain fewer emitting grains.