Dynamics and Atomic Processes in the Symbiotic Star AG Peg as Derived from Its Emission Line Spectrum

Sammanfattning: The spectra of symbiotic stars are shown to frequently contain numerous fluorescence lines caused by Photo-excitation by Accidental Resonance (PAR). So far, most work involving fluorescence in stellar spectra has been assigned to the search of new PAR mechanisms, which can explain the presence of certain emission lines. This is taken a step further as the PAR pumped emission lines are analyzed together with their pumping sources, which have enabled us to derive properties such as wind velocities, structure and opacities for the emitting plasma of the symbiotic star AG Peg. Furthermore, a powerful temperature diagnostic tool involving H Ly alpha pumped Fe~II lines is tested on the Weigelt Blobs of Eta Car, resulting in a temperature estimate of 3500 K. A majority of the observed ultraviolet emission lines in spectra of symbiotic stars are also explained in terms of population mechanism and locataion of origin. New ideas about the structure and evolution of symbiotic stars are discussed.