NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-08-18 T02:38:33 PDT
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For refcode 1987ApJ...316..573V:
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Copyright by American Astronomical Society. Reproduced by permission
1987ApJ...316..573V Broad, variable absorption lines in the Seyfert Galaxy NGC 3516 - Probing the structure of the emission-line regions G. Mark Voit, J. Michael Shull, and Mitchell C. Begelman Abstract. Nineteen short-wavelength IUE archive images were analyzed in order to probe the structure of the active nucleus in NGC 3516, an SB0 Seyfert I galaxy. The measurements of these features are presented, and the strength, variability, and morphology of the emission and absorption lines and their relation to the continuum are analyzed. It is shown that the absorption must arise within 10 pc of the nonthermal continuum source and that its variability must stem from changes in the velocity space coverage of clouds optically thin to the Lyman continuum. Two possible sites of absorption are discussed: dense clouds in the narrow-line region and optically thin clouds in the broad-line region. A theoretical model that explains the anticorrelation of C IV absorption with continuum flux is described. Key words: ABSORPTION SPECTRA, GALACTIC NUCLEI, GALACTIC STRUCTURE, LINE SPECTRA, SEYFERT GALAXIES, ULTRAVIOLET SPECTRA, CARBON, IUE, LYMAN SPECTRA, MOLECULAR CLOUDS, NONTHERMAL RADIATION
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