The Drop during Less than 300 days of a Dusty White Dwarf's Infrared Luminosity

TL;DR

This study reports a rapid 35% decrease in infrared luminosity of a white dwarf's dust disk within 300 days, suggesting dynamic disk changes possibly caused by a recent impact or disk instability.

Contribution

It provides the first detailed observation of a significant and rapid infrared flux decrease in a white dwarf's dust disk, highlighting the potential for high-cadence infrared studies.

Findings

Infrared flux decreased by ~35% in less than 300 days.

The inner disk radius likely increased due to impact or disk instability.

High-sensitivity infrared observations are crucial for studying white dwarf disks.

Abstract

We report Spitzer/IRAC photometry of WD J0959-0200, a white dwarf that displays excess infrared radiation from a disk, likely produced by a tidally disrupted planetesimal. We find that in 2010, the fluxes in both 3.6 $\mu$m and 4.5 $\mu$m decreased ~ 35% in less than 300 days. The drop in the infrared luminosity is likely due to an increase of the inner disk radius from one of two scenarios: (i) a recent planetesimal impact; (ii) instability in the circumstellar disk. The current situation is tantalizing; high sensitivity, high cadence infrared studies will be a new tool to study the interplay between a disk and its host white dwarf star.