The spectral energy distribution of protoplanetary diss around Massive
  Young Stellar Objects
  We investigate the effect of ionising radiation from Massive Young Stellar
Objects impinging on their emerging spectral energy distribution. By means of
detailed radiative transfer calculations including both the gaseous and dust
phase of their surrounding protoplanetary discs we highlight the importance of
modelling both phases simultaneously when interpreting observations from such
objects. In particular we find that models that only include dust may lead to
incorrect conclusions about the inner disc evolution. Furthermore the omission
of gas from models overproduces far-infrared and sub-millimiter fluxes with the
result that derived dust masses may be underestimated by a factor of two in
some cases. Finally free-free emission from the ionised component of gaseous
discs causes the slope of the dust emission in the sub-mm and mm regime to
appear flatter, resulting in incorrectly modelling the dust properties, with
consequences on the derived disc masses, power law index of the surface density
profile and other disc properties.
