# Most white dwarfs with detectable dust discs show infrared variability

## TL;DR

Infrared flux variations are common among dusty white dwarfs, indicating dynamic dust production and challenging existing static disc models, thus highlighting the importance of ongoing infrared monitoring.

## Contribution

This study provides the first long-term infrared variability data for dusty white dwarfs, revealing frequent flux changes and complex behaviors not explained by static models.

## Key findings

- Over half of known dusty white dwarfs show infrared variability.
- Flux variations suggest ongoing dust production and collisional processes.
- Infrared variability challenges the traditional flat disc model.

## Abstract

Archival data from the WISE satellite reveals infrared flux variations of tens of per cent around numerous dusty white dwarfs. Data spanning more than seven years reveal more than half of known systems are varying in the 3.4 micron band, while the 4.6 micron data are challenging to interpret due to lower signal-to-noise. The sparsely-sampled data limit interpretation, but the heterogeneous light curves suggest each source may be idiosyncratic, where there maybe competing processes operating on different time-scales. Collisions are likely driving the observed decays in flux, and this finding suggests that dust production is operating more often than indicated by previous observations. The observed variation is at odds with the canonical flat disc model in isolation, and underscores the need for infrared monitoring of these evolved planetary systems to inform the next generation of theoretical models.