THE TRANSFER OF RADIATION IN GALACTIC NUCLEI - DUSTY HOT-SPOTS IN THESTARBURST GALAXY M-82

We compute the equations of radiative transfer for the nucleus of a ga laxy assuming that the dust is heated by stars. The stars are distribu ted over a wide volume of the nucleus. It is an important aspect of ou r model that dust temperatures vary not only on a galactic scale, but change also locally in the hot spots around luminous OB stars. Because of the often copious UV radiation field in a galactic nucleus and obs ervational evidence in starburst galaxies we also consider in our mode l the presence of small grains and polycyclic aromatic hydrocarbons (P AHs) which both undergo temperature fluctuations and therefore strongl y influence the near and mid IR part of the spectrum. We demonstrate t he deficiency of those approximations which neglect either the hot spo ts or the emission by small grains or treat the stars as a point sourc e located in the center of the galactic nucleus. Our method is applied to the starburst galaxy M 82. The overall spectrum, including PAH fea utres is fitted as well as the observed source sizes between near IR t o millimetre wavelengths.