THE POLARIZED SPECTRUM OF THE FE II-RICH BROAD ABSORPTION-LINE QSO IRAS-07598+6508

We present IUE spectrophotometry and optical spectropolarimetry of the ultraluminous, extreme Fe II-emitting QSO IRAS 07598+6508. We find br oad absorption troughs from high- and low-ionization species, showing that this object is a member of the class of rare low-ionization broad absorption line (BAL) QSOs. Compared with non-BAL QSOs, the spectral energy distribution is reddened by E(B - V) similar to 0.12, and the H alpha/H beta ratio is even more reddened with E(B - V) similar to 0.4 5. The broad emission lines are unpolarized. We see broad Na I lambda 5892 absorption in the unpolarized continuum, but not in the polarized continuum (at the 5-6 sigma level). The polarized continuum rises smo othly toward shorter wavelengths with F-lambda proportional to lambda( -2). We argue that a normal QSO continuum is polarized by scattering f rom a region within, or very near, the broad emission line region (BEL R). Thus there are at least three distinct light paths to the observer : a dusty path from the BELR; a direct path traced by the unpolarized continuum, passing through dust and low-ionization gas (Na I); and ano ther relatively unobscured path followed by scattered continuum. This provides direct evidence that a BAL region and dust only partially cov er the central QSO. Ultraluminous active galactic nuclei, including IR AS 07598+6508, appear no more IR-luminous than non-IRAS-selected QSOs, and have normal L(IR)/L(opt) ratios when the optical luminosities are corrected for reddening. BALs and reddening occur only along some sig ht lines, and the parent population of BAL QSOs appear to be ''normal' ' QSOs.