We use Hubble Space Telescope UV and optical spectra of the narrow-line Seyfert 1 ( NLS1 ) galaxy Akn 564 to investigate its internal reddening and properties of its emission-line and intrinsic UV absorption gas .
We find that the extinction curve of Akn 564 , derived from a comparison of its UV/optical continuum to that of an unreddened NLS1 , lacks a 2200 Å bump and turns up towards the UV at a longer wavelength ( 4000 Å ) than the standard Galactic , LMC , and SMC curves .
However , it does not show the extremely steep rise to 1200 Å that characterizes the extinction curve of the Seyfert 1 galaxy NGC 3227 .
The emission-lines and continuum experience the same amount of reddening , indicating the presence of a dust screen that is external to the narrow-line region ( NLR ) .
Echelle spectra from the Space Telescope Imaging Spectrograph show intrinsic UV absorption lines due to Ly \alpha , N V , C IV , Si IV , and Si III , centered at a radial velocity of - 190 km s ^ { -1 } ( relative to the host galaxy ) .
Photoionization models of the UV absorber indicate that it has a sufficient column ( N _ { H } = 1.6 x 10 ^ { 21 } cm ^ { -2 } ) and is at a sufficient distance from the nucleus ( D > 95 pc ) to be the source of the dust screen .
Thus , Akn 564 contains a dusty “ lukewarm absorber ” similar to that seen in NGC 3227 .