FREQUENCY-DEPENDENT RADIATION TRANSFER IN PROTOSTELLAR DISKS

The distributions of dust temperatures and mean radiation intensities in axially symmetric dusty disks are calculated within the framework o f the flux-limited diffusion approximation. A multi-component dust mod el, consisting of amorphous carbon and silicate grains, which are coat ed with ''dirty ice'', is employed. After determination of the dust te mperatures a ray-tracing procedure is used to calculate the spectral a ppearance of the disk at varying inclinations and to produce isophote maps at selected frequencies. The spatial distribution of dust tempera tures resulting from these calculations reflect the shape of a disk's density distribution and do not display a simple (distance)(-a) power law. The spectra calculated from the same disk model at different incl inations can vary over a wide range. It is therefore often not possibl e to derive parameters of a disk - in particular its evolutionary stat e - from the spectrum alone. It is not recommended to infer the existe nce of planets by using simple temperature power law fits to disk spec tra in combination with simple power law dust opacities.