title: Refining dust evolution models in protoplanetary disks with ALMA

authors: Pinilla, P.; Birnstiel, T.; Benisty, M.; Ricci, L.; Uribe, A.; Dullemond C. P.

abstract: Radio-observations of protoplanetary disks have revealed the presence of millimeter-size dust particles in the outer regions of disks. However, this feature is not expected from a theoretical point of view, since pebbles cannot grow due to destructive collisions and  rapid inward drift. During the last decades, this has been a puzzle that different theoretical efforts have tried to solve. The presence of pressure bumps  in a disk has been proposed as a solution to moderate the rapid migration of particles and decrease the high destructive relative velocities. Using a disk model that includes dust coagulation and fragmentation, we consider pressure inhomogeneities, such as the ones predicted by MHD simulations,  and we demonstrate that the trapping of mm-dust particles in the outer regions of the disk is possible on million years time scales (Pinilla et al. 2012, A&A, 538, A114). The high spatial resolution and sensitivity that ALMA will provide  us is essential to detect  possible ring structures (as the result of pressure bumps) at the distances of either the Taurus Auriga or Ophiucus star-forming regions. In addition, we explore how  our dust evolution models can reproduce the ring-like emission of some transitional disk considering an open gap  by  a massive planet. ALMA will again be the key for evaluate our models, since calculating the difference of the mm-slope inside and outside these rings, we can test if these structures are particle traps where dust accumulates and grows over mm-sizes (Pinilla et al. 2012, submitted to A&A).