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F. Hamann (University of Florida), H. Netzer (Tel Aviv University), J. C. Shields (Ohio University)
We discuss new Hubble Space Telescope spectroscopy of the radio-loud quasar, 3C 288.1. The data cover ~590 Å\ to ~1610 Å\ in the quasar rest frame. They reveal a wealth of associated absorption lines (AALs) with no accompanying Lyman-limit absorption. The metallic AALs range in ionization from CIII and NIII to NeVIII and MgX. We use these data and photoionization models to derive the following properties of the AAL gas: 1) There are multiple ionization zones within the AAL region, spanning a factor of at least ~50 in ionization parameter. 2) The overall ionization is consistent with the ``warm'' X-ray continuum absorbers measured in Seyfert 1 nuclei and other QSOs. However, 3) the column densities implied by the AALs in 3C 288.1 are too low to produce significant bound-free absorption at any UV--X-ray wavelengths. Substantial X-ray absorption would require yet another zone, having either a much higher ionization or much lower velocity dispersion than the main AAL region. 4) The total hydrogen column density in the AAL gas is log NH (cm-2) = 20.2. 5) The metallicity is roughly half solar. 6) The AALs have deconvolved widths of ~900 km/s and their centroids are consistent with no shift from the quasar systemic velocity (conservatively within ±1000 km/s). 7) There are no direct indicators of the absorber's location in our data, but the high ionization and high metallicity both suggest a close physical relationship to the quasar and/or its host galaxy.
Finally, the UV continuum shape gives no indication of a ``blue bump'' at higher energies. There is a distinct break of unknown origin at ~1030 Å, and the decline toward higher energies (with spectral index \alpha = -1.73, for f\nu\propto \nu\alpha) is even steeper than a single power-law interpolation from 1030 Å\ to soft X-rays.