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

We report Spitzer/Infrared Array Camera 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??m and 4.5??m decreased by ~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: (1) a recent planetesimal impact; (2) 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.