Splitting of absorption lines in 3C 191

Abstract

Spectroscopic observations of the quasar 3C 191 have been made at a higher dispersion than in previous studies in an attempt to detect absorption from the excited fine-structure level of the ground state of C II. It was found that the previously studied absorption system is split into two systems which show apparent line-locking on the C IV 1550-A doublet. Both systems show a similar and wide range of ionization. The results are interpreted in terms of a multiple-cloud model which is photoionized by a central source, and possible implications for the ionization structure in QSOs as a whole are discussed.