2025MNRAS.538.1944N

In this paper, we conduct a detailed study on the effect of radiative torque disruption (RATD) mechanism on the fragmentation of micrometre-sized dust grains into nanoparticles within the heliosphere. We start by estimating the disruption time-scales for dust grains under various centrifugal stresses. Our numerical calculations demonstrate that RATD is a highly effective mechanism for breaking down micrometre-sized grains, producing nanoparticles more efficiently than other fragmentation processes. RATD also prevents micrometre-sized grains from being expelled by radiation pressure. Our findings indicate that the location of the present water snow line depends not only on temperature but also on the size of dust grains. For smaller grains, the snow line can shift outward beyond the position defined by thermal sublimation. Furthermore, we model the size distribution of dust grains modified by the RATD mechanism using a simplified model, showing that rotational disruption significantly decreases the number density of micrometre-sized grains while substantially increasing the number density of submicrometre-sized grains. However, the fraction of dust grains aligned at high-J attractors by radiative torques less than 80 per cent can considerably weaken the effect of RATD on the grain size distribution. Finally, we suggest several experiments that could potentially test the RATD mechanism and discuss the uncertainties of our model in more realistic applications to heliospheric dust.