Outflow in the nucleus of the Seyfert I galaxy NGC 3783

Averaged low-resolution IUE spectra of the Seyfert I galaxy NGC 3783 at two brightness levels are presented. The wavelength interval 1250-1400 A, which is essentially free of emission lines in active galaxies, contains two absorption lines at 1303 A and 1335 A. The line at 1303 A shows, in contrast to the line at 1335 A, considerable variations with continuum brightness. This is interpreted as variations in the Si III (4) metastable absorption at 1294-1305 A, with an outflow velocity of about 3000 km/s. C IV absorption at the same velocity is present when the galaxy is bright. This indicates the presence of outflow of material, which is optically thin to the variable ionizing UV continuum. The variable UV continuum has to extend at least until 50 eV (about 250 A). 10 references