This is a schematic view of a young forming star that accrets mass from a surrounding proto-planetary disk. The star (in the center) has a magnetosphere (red streamlines) which disrupts the disk in proximity of the star (in the so-called truncation radius) forcing the matter to accrete onto the star through accretion columns (green streams that link the disk to the star). At large distances from the star, the disk has a complex internal structure (right) where molecules and dust are formed. In particular, grains of dust grow up in the disk interior (see small yellow dots on the left of the model), eventually triggering the formation of proto-planets from the accumulation of these grains. The model also shows where giant planets as Jupiter are belived to form in the disk (large green spheres on the left).