Chemistry Along Accretion Streams in a Viscously-Evolving Protoplanetary
  Disk
  The composition of a protoplanetary disk is set by a combination of
interstellar inheritance and gas and grain surface chemical reactions within
the disk. The survival of inherited molecules, as well as the disk in situ
chemistry depends on the local temperature, density and irradiation
environment, which can change over time due to stellar and disk evolution, as
well as transport in the disk. We address one aspect of this coupling between
the physical and chemical evolution in disks by following accretion streamlines
of gas and small grains in the disk midplane, while simultaneously taking the
evolving star into account. This approach is computationally efficient and
enables us to take into account changing physical conditions without reducing
the chemical network. We find that many species are enhanced in the inner disk
midplane in the dynamic model due to inward transport of cosmic-ray driven
chemical products, resulting in, e.g., orders-of magnitude hydrocarbon
enhancements at 1 au, compared to a static disk. For several other chemical
families, there is no difference between the static and dynamic models,
indicative of a robust chemical reset, while yet others show differences
between static and dynamic models that depend on complex interactions between
physics and chemistry during the inward track. The importance of coupling
dynamics and chemistry when modeling the chemical evolution of protoplanetary
disks is thus depends on what chemistry is of interest.
