CHEMICAL EVOLUTION IN ACCRETION DISKS IN VIEW OF MASS TRANSPORT MECHANISMS

摘要

The chemical composition of planets and their atmospheres will depend on the chemical state of accretion disks in which they form. Therefore, we have to find out which processes determine the chemistry in different regions of protoplanetary disks. In this paper we will discuss the influence of mass transport processes on the chemical evolution of a protoplanetary accretion disk. Both mass transport by diffusion in a multi-component system and advective transport such as the accretion flow within non-steady protoplanetary accretion disks may transport chemical species beyond the snowline where cometesimals form. We should also note that chemistry may easily couple back to disk dynamics by determining the ionization state and cooling rates via the abundance of electrons, metals, and key molecules. Two different approaches can be used to study the combined effects of dynamics and chemistry: Models based on a reduced chemical network and fully developed (magneto)-hydrodynamics or models with extended chemical networks and simplified hydrodynamics. We used the latter approach to study the chemical evolution in accretion disks taking into account radial and vertical mass transport processes. The results demonstrate the strong influence transport processes have on disk chemistry.