# Externally-polluted white dwarfs with dust disks

## TL;DR

This study uses Spitzer Space Telescope data to identify and analyze dust disks around externally-polluted white dwarfs, providing insights into planetary debris accretion processes.

## Contribution

First infrared observations of multiple polluted white dwarfs revealing dusty disks and supporting asteroid accretion hypotheses.

## Key findings

- GD 40, GD 133, PG 1015+161 have flat, opaque dust disks.
- GD 56 shows dust excess with complex grain temperature requirements.
- GD 40's metals likely originate from tidally disrupted asteroid with chondritic composition.

## Abstract

We report Spitzer Space Telescope photometry of eleven externally-polluted white dwarfs. Of the nine stars for which we have IRAC photometry, we find that GD 40, GD 133 and PG 1015+161 each has an infrared excess that can be understood as arising from a flat, opaque, dusty disk. GD 56 also has an infrared excess characteristic of circumstellar dust, but a flat-disk model cannot reproduce the data unless there are grains as warm as 1700 K and perhaps not even then. Our data support the previous suggestion that the metals in the atmosphere of GD 40 are the result of accretion of a tidally-disrupted asteroid with a chondritic composition.