An ultraviolet and optical study of the broad-line radio galaxy 3C 382.

Abstract

Ultraviolet spectra covering 13 separate epochs are presented for the extreme broad-line radio galaxy 3C 382. These show marked variability in both lines and continuum on a time-scale less than about 1 yr. The C IV 1550 A and L-alpha 1216 A lines follow the changes in the ultraviolet continuum but appear to have different profiles, the L-alpha 1216 having a relatively stronger core. By comparison with the present and published optical data, it is apparent that L-alpha and C IV have variability properties different from those of the Balmer lines and Mg II 2800 A. L-alpha 1216 A becomes weaker relative to the Balmer lines as the ultraviolet continuum diminishes (an observation that places important constraints on ionization models for the broad line radio galaxies). A long-slit spectrum obtained with the newly commissioned INT telescope shows extended emission lines at up to 17 arcsec (25 kpc, H = 50 km/s per Mpc) from the nucleus and demonstrates a large velocity gradient in the narrow-line gas across the nucleus.