The ultraviolet absorption spectrum of NGC 4151.

Abstract

The analysis of all available low dispersion, short wavelength, large aperture IUE spectra of NGC 4151 taken prior to March 1982 shows a linear correlation between the depth of the absorption lines and the strength of the underlying emission; the absorption lines vanish while the continuum is still measurable. This is interpreted as being due to an absorbing cloud covering a compact, variable central source and the broad-line emitting region while a second, non-variable, continuum source (possibly a jet) lies at some distance, uncovered by the absorbing cloud.