Frequency dependent radiation transfer in protostellar disks

Cordula Sonnhalter, Thomas Preibisch & Harold W. Yorke

Astronomy and Astrophysics 299, 545, (1995)


The distribution of dust temperatures and mean radiation intensities in axially symmetric dusty disks are calculated within the framework of the flux-limited diffusion approximation. A multi-component dust model, consisting of amorphous carbon and silicate grains which are coated with `dirty ice', is employed. After determination of the dust temperatures a ray-tracing procedure is used to calculate the spectral appearance of the disk at varying inclinations and to produce isophote maps at selected frequencies.

The spatial distribution of dust temperatures resulting from these calculations reflect the shape of a disk's density distribution and do not display a simple power law. The spectra calculated from the same disk model at different inclinations can vary over a wide range. It is therefore often not possible to derive parameters of a disk - in particular its evolutionary state - from the spectrum alone. It is not recommended to infer the existence of planets by using simple temperature power law fits to disk spectra in combination with simple power law dust opacities.

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