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|Spectral classification of emission-line galaxies|
A revised method of classification of narrow-line active galaxies and HII region-like galaxies is proposed. It involves the line ratios whichtake full advantage of the physical distinction between the two types ofobjects and minimize the effects of reddening correction and errors inthe flux calibration. Large sets of internally consistent data are used,including new, previously unpublished measurements. Predictions ofrecent photoionization models by power-law spectra and by hot stars arecompared with the observations. The classification is based on theobservational data interpreted on the basis of these models.
|Empirical results from a study of active galactic nuclei|
Spectrophotometric observations are presented for emission-linegalaxies. When combined with previous Lick Observatory measurements,they are used to deduce criteria that allow the Seyfert 2 phenomena tobe quantitatively isolated from the narrow-emission-line galaxies. Thesecriteria are based on the finding that galaxies with forbidden line OIII 5007 A/H-beta ratios lower than 3 have emission line widths that areusually considerably smaller than the widths in galaxies with forbiddenline O III 5007 A/H-beta ratios greater than 3. In addition, large He II4686 A/H-beta ratios are consistent with forbidden line O III 5007A/H-beta ratios greater than 3. The physical conditions in thenarrow-line regions of Seyfert 1 galaxies are compared with those inSeyfert 2 galaxies. Significant differences are found for thetemperature-sensitive forbidden line O III ratio, and for the luminosityof Fe VII forbidden line 6087 A relative to the luminosity of thelow-ionization forbidden lines.
|Accurate Optical Positions of Arakelian Galaxies|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1981AJ.....86..820K&db_key=AST
|Galaxies of high surface brightness|
Two lists are presented which contain 621 galaxies whose surfacebrightness, as derived from their apparent magnitudes, is at least 22.0magnitudes from an area of 1 sq arcsec. The lists were compiled in anattempt to verify observationally a possible correlation between surfacebrightness and nuclear activity. Four percent of all the galaxies in anarea of 4.5 sr at declinations higher than -3 deg and galactic latitudesgreater than 20 deg are listed, including 30 Markarian, 29 Zwicky, and 7blue Haro galaxies. A morphological study of 130 of the galaxiesindicates that about half are elliptical or lenticular, 50 are compactor peculiar, and that there is an excess of elliptical and lenticularobjects in comparison with a random sample. Notes on the morphologicaltypes and colors of the galaxies are provided along with identificationcharts.
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