Variable C IV absorption in the Seyfert galaxy NGC 5548 : a connection to broad absorption line quasi-stellar objects ?

Variable absorption components in the broad emission lines of Seyfert 1 galaxies is examined. In an IUE the broad-line region must be at least partially covered by the absorbing region and the central wavelength of the broad-line region corresponds to that of the maximum absorption. Standard broad-line clouds cannot account for the absorption feature and the absorbing material must be optically thin and dispersed in velocity space. We propose a relationship between broad absorption line (BAL) QSOs and Seyfert 1 galaxies with absorption, and we suggest that the latter may be a low-luminosity 1ow-redshift manifestation of the BAL phenomenon in quasars. The high frequency of occurrence may represent a statistical effect of outflow viewing angle on the sky.