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Steps toward determination of the size and structure of the broad-line region in active galactic nuclei. I - An 8 month campaign of monitoring NGC 5548 with IUEEmission-line and UV continuum observations of the type I Seyfert galaxy NGC 5548 were carried out for a period of 8 months with the IUE satellite. It was found that both the continuum shape and the line ratios of NGC 5548, while being not unusual for type I Seyfert galaxies, are strongly variable. The UV continuum flux and broad emission line fluxed went through three large maxima and three deep minima; the ratio of miximum to minimum flux was about 4.5 for the continuum at 1350 A. The N V and the He II emission lines exhibited maximum-to-minimum flux ratios as high as those of the continuum; other ionization lines (Ly-alpha, C IV, and C III) exhibited smaller amplitude fluctuations, with the smallest being recorded for the Mg II line (about 1.3). It was found that, except for Mg II, the emission-line variations correlated extremely well with those of the 1350-A continuum.
Document ID
19910034435
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Clavel, J.
(European Space Agency. ESA Tracking Station Madrid, Spain)
Wamsteker, W. A.
(IUE Observatory Madrid, Spain)
Reichert, G. A.
(European Space Agency. ESA Tracking Station Madrid, Spain)
Crenshaw, D. M.
(NASA Goddard Space Flight Center; Computer Sciences Corp. Greenbelt, MD, United States)
Alloin, D.
(Paris Observatoire, Meudon, France)
Date Acquired
August 15, 2013
Publication Date
January 1, 1991
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 366
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
91A19058
Distribution Limits
Public
Copyright
Other

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