Broad-band and Hα surface photometry of the central regions of nearby active galaxies – I. Observations |
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| Authors: | Miguel Sánchez-Portal Ángeles I Díaz Roberto Terlevich † Elena Terlevich ‡ Mar Álvarez Álvarez Itziar Aretxaga |
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| Institution: | Dpto. de Física Teórica, C-XI, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain; LAEFF/INTA, PO Box 50727, 28080 Madrid, Spain; Institute of Astronomy, Madingley Road, Cambridge CB3 0HA; Instituto Nacional de Astrofı´sica, Óptica y Electrónica, Tonantzintla, Puebla, Mexico |
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| Abstract: | Broad-band V , R and I and narrow-band H α CCD surface photometry of a sample of 24 active and three normal nearby galaxies is presented, in order to study their morphological and structural properties. This first paper presents the observations, data reduction and processing techniques used; the main characteristics of the central regions of the sample galaxies are derived from broad-band and H α images; broad-band surface brightness and colour profiles are presented; based on the inspection of individual images and the examination of the radial variation of ellipticity and polar angle, the morphological class of the sample objects is revised: several objects previously classified as non-barred or unclassified are found to be barred galaxies. A high fraction (∼71 per cent) of the objects that present any kind of nuclear activity are barred. This proportion is even higher (∼87 per cent) if only Seyfert galaxies are considered. This result can reinforce the clues about the connection between bars and nuclear activity as a fuelling mechanism that can trigger and sustain nuclear activity. |
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| Keywords: | galaxies: active galaxies: fundamental parameters galaxies: photometry |
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