A study of emission lines variability of the active galaxy PKS 0521-365.

Abstract

Optical spectrophotometry of the active galaxy PKS 0521-365 over a period of 7 years is reported, together with the analysis of IUE archival spectra. The Hα emission line intensity varied by more than a factor of 2 during the monitoring. Similar amplitude variations are observed in the optical and UV continuum, which however are not simply correlated with the line intensity variations. The broad component of Hα is found to be asymmetric with a longer extension towards the red. The Lyα, the only line detected in the UV band, appears symmetric and exhibits marginal intensity variability.