Transport processes and chemical evolution in steady accretion disk flows

Abstract

We study the influence of mass transport processes on the chemical evolution in a protoplanetary accretion disk. Local transport processes by advection as well as global transport processes by diffusion are taken into account. Concerning the multi-component system only diffusion in the vertical direction was taken into account. Depending on the transport properties, different schemes are explored to couple/decouple the physical and chemical evolution. Our model is based on a simplified description of hydrodynamics in terms of a steady 1+1-D-α-disk model and includes the kinetics of an extended chemical network of about 250 species. We restrict our calculations to the inner planet formation zone within a distance to the central star of 10 AU. Vertical mixing does change the global chemical evolution as it is demonstrated in detail through a discussion of the chemistry of sulphur-bearing molecules. In addition, the influence of the local disk structure on the chemical evolution is analysed. Our results demonstrate that the chemical evolution is influenced globally by mass transport processes. However, in addition to mass transport processes, information about the local conditions, which determine the kinetics, is still needed in order to analyze the chemical evolution.