KECK SPECTROPOLARIMETRY OF THE RADIO GALAXY 3C-234

We present high signal-to-noise ratio spectropolarimetric data of 3C 2 34 observed with the 10 m Reck telescope. The data were obtained with the polarimeter on the Low Resolution Imaging Spectrometer, covering a wavelength range of 3900-9000 Angstrom at moderate resolution. They s how that broad Ha and HP are apparently polarized higher than the adja cent continuum but at the same position angle perpendicular to the rad io axis, similar to the behavior of many Seyfert 2 galaxies reported b y Tran. As proposed for the Seyfert 2 galaxies, we interpret the curre nt data in terms of the presence of a second extended continuum, and d erive a high 25% intrinsic polarization for the hidden continuum and b road emission lines, due to scattering. We are able to decompose the o bserved spectrum of 3C 234 into at least three components comprising: (a) a scattered (polarized) continuum plus broad emission lines from t he obscured active galactic nucleus, (b) an extended, unpolarized cont inuum plus narrow emission lines resembling a typical narrow-line radi o galaxy spectrum, and (c) a stellar component from the underlying hos t galaxy. A combination of high extinction experienced by the scattere d radiation and dilution by the unreddened extended continuum, which m akes up nearly half of the starlight-corrected total flux, causes the slight increase to the red of the polarization after correction for st arlight dilution has been applied. Our data show that, free of the obs curing material or from another direction, 3C 234 would be a luminous quasar, thus providing support for the unification of quasars and radi o galaxies. These and other observations suggest that spatially extend ed continuum in AGNs may be quite common and thus should be taken into account when their intrinsic nuclear continua are studied. (C) 1995 A merican Astronomical Society.