SIMBAD references

Fluorescent excitation of spectral lines is demonstrated as a function of temperature-luminosity and the distance of the emitting region from the central stars of planetary nebulae (PNs). The electron densities and temperatures are determined, and the method is exemplified through a detailed analysis of spectral observations of a high-excitation PN, NGC 6741. Fluorescence should also be important in the determination of element abundances. It is suggested that the method could be generally applied to determine or constrain the luminosity and the region of spectral emission in other intensively radiative sources such as novae, supernovae, and active galactic nuclei.