Photochemical-dynamical models of externally FUV irradiated
  protoplanetary discs
  There is growing theoretical and observational evidence that protoplanetary
disc evolution may be significantly affected by the canonical levels of far
ultraviolet (FUV) radiation found in a star forming environment, leading to
substantial stripping of material from the disc outer edge even in the absence
of nearby massive stars. In this paper we perform the first full radiation
hydrodynamic simulations of the flow from the outer rim of protoplanetary discs
externally irradiated by such intermediate strength FUV fields, including
direct modelling of the photon dominated region (PDR) which is required to
accurately compute the thermal properties. We find excellent agreement between
our models and the semi-analytic models of Facchini et al. (2016) for the
profile of the flow itself, as well as the mass loss rate and location of their
"critical radius". This both validates their results (which differed
significantly from prior semi-analytic estimates) and our new numerical method,
the latter of which can now be applied to elements of the problem that the
semi--analytic approaches are incapable of modelling. We also obtain the
composition of the flow, but given the simple geometry of our models we can
only hint at some diagnostics for future observations of externally irradiated
discs at this stage. We also discuss the potential for these models as
benchmarks for future photochemical-dynamical codes.
