Abstract
view Abstract Citations (42) References (59) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Search for Variations of [Fe VII] Lambda 6087 and [Fe X] Lambda 6375 in High-Ionization Seyfert Galaxies Veilleux, Sylvain Abstract The results of a study of the emission lines [Fe X] λ6375 and [Fe VII] λ6087 in 18 high-ionization active galaxies are presented. The galaxies were selected on the bases of the strength of [Fe X] λ6375 and the availability of spectra taken at different epochs. The time interval spanned by the data ranges from a few months to 10 yr with, on average, three sets of observations per object. In contrast with most of the previous investigations, comparisons are made between spectra obtained with the same instrument and, when possible, with the same observational setup. The line ratios [Fe X] λ6375 /[O I] λ6300,[Fe X]λ6375/[S II] λλ6716, 6731, [Fe VII] λ6087/[O I] λ6300, and [Fe VII] λ6087/[S II] λλ6716, 6731 were measured for each object and variations of λ6375 and λ6087 were tested under the assumption of constant [O I] and [S II] fluxes. The best candidate for variations of [Fe VII] and [Fe X] is NGC 5548; seven other galaxies show possible variations of one or both of these lines. The timescale for the variations observed in NGC 5548 is less than 3 yr. Many potential sources of errors were taken into account in the interpretation of the results, such as measurement uncertainties, sky subtraction, calibration into energy units, afterglow, contamination by other emission lines, atmospheric absorption features, underlying stellar continuum, and atmospheric conditions during observation. Publication: The Astronomical Journal Pub Date: June 1988 DOI: 10.1086/114766 Bibcode: 1988AJ.....95.1695V Keywords: Active Galactic Nuclei; Emission Spectra; Ionization Potentials; Line Spectra; Seyfert Galaxies; Variable Stars; Error Analysis; Iron; Meteorology; Astrophysics; RADIO SOURCES: GALAXIES; GALAXIES: SEYFERT full text sources ADS | data products SIMBAD (18) NED (18)
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