Abstract

In the context of protoplanetary disk evolution, the aerodynamic coupling of dust and gas predicts the accumulation of the larger dust grains in local pressure maxima. The MWC758 disk is indeed one of the best examples for dust trapping in anticyclonic vortices, where the pile up of dust may lead to grain growth. Long wavelengths observations traces clumpy distributions of large grains, whose morphology can be linked to physical conditions. Yet, new observations reveal a faint and extended component at 1cm, without counterparts in at 1mm. This radio continuum component may represent an excess microwave emission (EME), and could stem from spinning dust radiation. This identification may open a new window on the very small grain population in protoplanetary disks, and is important to separate genuine emission from the larger grains.