Intrinsic Absorption and Emission Lines in Seyfert Galaxies

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Abstract
RecentHSTspectra indicate that a large fraction of Seyfert 1 galaxies have UV absorption lines that are intrinsic to the active nucleus or its environment.IUEmonitoring or multipleHSTobservations of several sources show that many absorption lines are variable, either as a result of mass motion across the line-of-sight or of changing ionization within the gas in response to variations in the ionizing continuum. The UV absorbers may be related to the warm absorbers seen in the X-ray spectra of many Seyfert galaxies, but a direct connection between the two has not been made. Some of the absorption lines may arise in the emission-line regions in the nucleus or host galaxy, providing valuable clues to their nature.