On the nature of ultraviolet and X-ray absorption in NGC 3783

The Seyfert 1 nucleus of NGC 3783 shows intrinsic absorption in ultraviolet (UV) resonance lines as well as in soft X-rays. We review existing measurements of these features and use them to place constraints on the physical conditions in the absorbing media. We find that the observed column densities are consistent with a single-phase, photoionized plasma responsible for absorption in both bandpasses. although alternative scenarios in which the UV and X-ray continuum sources are covered by distinct clouds are not excluded. If the UV and X-ray absorbers constitute: a single medium in at least approximate ionization equilibrium with the nuclear radiation field, observed variability in the strength of absorption can be used to derive a lower bound on the absorber's electron density of n(c) greater than or similar to 50 cm(-3). This result additionally implies an upper limit of about 30 pc for the separation between the nuclear continuumn source and the absorbing plasma.