White dwarf WD 1145+017 is orbited by several clouds of dust , possibly emanating from actively disintegrating bodies .
These dust clouds reveal themselves through deep , broad , and evolving transits in the star ’ s light curve .
Here , we report two epochs of multi-wavelength photometric observations of WD 1145+017 , including several filters in the optical , K _ { \mathrm { s } } and 4.5 \mu m bands in 2016 and 2017 .
The observed transit depths are different at these wavelengths .
However , after correcting for excess dust emission at K _ { \mathrm { s } } and 4.5 \mu m , we find the transit depths for the white dwarf itself are the same at all wavelengths , at least to within the observational uncertainties of \sim 5 % -10 % .
From this surprising result , and under the assumption of low optical depth dust clouds , we conclude that there is a deficit of small particles ( with radii s \lesssim 1.5 \mu m ) in the transiting material .
We propose a model wherein only large particles can survive the high equilibrium temperature environment corresponding to 4.5 hr orbital periods around WD 1145+017 , while small particles sublimate rapidly .
In addition , we evaluate dust models that are permitted by our measurements of infrared emission .