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 IUE

Journal Article · Tue Jan 01 04:00:00 EST 1991 · Astrophysical Journal; (USA)

DOI:https://doi.org/10.1086/169540· OSTI ID:5993765

Clavel, J; Wamsteker, W A; Reichert, G A; Crenshaw, D M; Alloin, D ^[1]

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1. IUE Observatory, Madrid (Spain) NASA, Goddard Space Flight Center (USA) Computer Sciences Corp., Greenbelt, MD (USA) Paris Observatoire, Meudon (France)

Emission-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. 51 refs.

• OSTI ID: 5993765
• Journal Information: Astrophysical Journal; (USA), Journal Name: Astrophysical Journal; (USA) Vol. 366; ISSN ASJOA; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CORRELATIONS
EMISSION SPECTRA
GALAXIES
GALAXY NUCLEI
MATHEMATICS
MORPHOLOGY
SEYFERT GALAXIES
SPECTRA
SPECTROSCOPY
TIME-SERIES ANALYSIS
ULTRAVIOLET SPECTRA
VARIATIONS