THE SHORT-TERM DISAPPEARANCE OF THE BROAD-LINE REGION IN NGC-5548 - IMPLICATIONS FOR THE DUSTY TORUS MODEL

We model the dust distribution in NGC 5548. The dust is close enough t o the internal radiation source to account formally for the temporary disappearance of the broad lines in this galaxy. However, the extincti on by dust alone can barely explain the line disappearance. In additio n, the temporal behaviour of the Hbeta line can be well described by a simple model if we allow for intrinsic change of the source. These ar guments in favour of the intrinsic disappearance of broad lines in NGC 5548 cast some doubts upon the generality of the unified scheme for S eyfert 1 and Seyfert 2 galaxies.