AAS 196th Meeting, June 2000
Session 16. Galaxies and Quasars
Oral, Monday, June 5, 2000, 2:00-3:30pm, Lilac Ballroom

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[16.07] Recent Observations of Intrinsic UV Absorption Lines in Seyfert Galaxies with STIS

D.M. Crenshaw, S.B. Kraemer, J.R. Ruiz (CUA/GSFC)

We present recent observations of the intrinsic UV absorption lines in several Seyfert 1 galaxies with the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope (HST). Echelle observations of NGC 4151 on 1999 June 19 indicate that the continuum and broad emission lines were at a low state at this time. Consequently, strong low-ionization absorption lines appear in the spectra, including numerous metastable Fe II lines. A feature in the blue wing of the C IV emission line, identified as a transient C IV absorption line at high outflow velocity by Weymann et al., turns out to be a fine-structure Si II line. Our current work focuses on determining the physical conditions in different kinematic components of the absorption using detailed photoionization models.

Our STIS echelle observations of NGC 3783 on 2000 February 27 reveal that a new component of C IV and N V absorption has appeared since the last GHRS observation 5 years earlier, at a radial velocity of -800 km/sec relative to the systemic velocity. In addition, the component at -1400 km/sec has become much stronger and is present in Si IV, indicating a lower ionization state compared to the other components.

We have also obtained low-resolution UV spectra of the Seyfert 1 galaxy NGC 3227, which is characterized by significant reddening of the continuum and emission lines. In addition to saturated absorption from high-ionization lines, we detect strong absorption in the Si IV and Mg II lines. This confirms our prediction that a lukewarm absorber that occults much of the narrow-line region is responsible for the reddening (Kraemer et al. 2000), rather than a large neutral column or a dusty X-ray absorber.

The author(s) of this abstract have provided an email address for comments about the abstract: crenshaw@buckeye.gsfc.nasa.gov

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