Dynamical and chemical evolution of the protoplanetary nebula

The currently available information on the dynamical collapse of rotating protostellar clouds, the formation and properties of viscous accretion disks obtained from such numerical experiments, and the resulting constraints and consequences for the protoplanetary environment are reviewed. This information is used to develop a transport theory for dust and gas phases, and results obtained from this theory are presented. Possible modifications by intermittent turbulence are discussed, chemical fractionation effects are analyzed, and the heterogeneity on small scales as well as the homogeneity on large scales of the primitive bodies in the solar system is examined within the framework of this theory. It is concluded that a turbulent protoplanetary nebula has a number of appealing consequences, especially from a dynamical (angular momentum transport) and from a chemical point of view. If the turbulence is intermittent, it may also provide the fastest means of growing planets from the solid dust component, an important point, because the giant planets at least must have formed before the gaseous component of the disk had dissipated