Dust Resurgence in Protoplanetary Disks Due to Planetesimal-Planet Interactions

Observational data on the dust content of circumstellar disks show that the median dust content in disks around pre-main-sequence stars in nearby star-forming regions seems to increase from similar to 1 to similar to 2 Myr and then decline with time. This behavior challenges the models where the small dust grains steadily decline by accumulating into larger bodies and drifting inwards on a short timescale (<= 1 Myr). In this Letter we explore the possibility to reconcile this discrepancy in the framework of a model where the early formation of planets dynamically stirs the nearby planetesimals and causes high-energy impacts between them, resulting in the production of second-generation dust. We show that the observed dust evolution can be naturally explained by this process within a suite of representative disk-planet architectures.