Far-ultraviolet absorption lines in active galaxies.

Abstract

Attention is drawn to the far-ultraviolet absorption lines which have been discovered with IUE in a number of active nuclei. The properties of these lines are presented and discussed with emphasis on the following points: (i) the frequency of occurrence of far ultraviolet absorption lines (ii) a comparison between the properties of these lines and those of the broad absorption line systems in quasar spectra, and (iii) the relation between soft X-ray absorption and ultraviolet absorption lines. Detailed studies of individual objects are outside the scope of this article.