A study of a homogeneous sample of optically selected active galactic nuclei. III. Optical observations

We present CCD observations in BVR optical bands of the homogeneous sample of 42 Seyfert 1 galaxies, that we also observed in near-IR JHK bands (Zitelli et al. 1993; Danese et al. 1992). We have applied to these data the same analysis procedure used for the infrared images, with the aim of separating the galaxian and nuclear fluxes, as well as investigating the main characteristics of the hosts. Nuclear fluxes have been estimated with typical global errors of 0. 1 5 mag, while 0.3 mag errors are on.average associated to host galaxy magnitudes. It is shown that in half of the host galaxies the bulge contribute more than 40% to the total observed fluxes even within small apertures. In the sample galaxies disks are dominating over the bulge in the large majority of the cases, suggesting that a significant fraction of Seyfert galaxies could be late-type spirals. Moreover the galactic morphological parameters are in the ranges of typical spiral galaxies. The statistics of galactic colors show that the host galaxies tend to be bluer than the normal ones. This fact added to redder colors found in the IR-bands strengthens the suggestion that in Seyfert galaxies the star formation is on average enhanced.

We present CCD observations in BVR optical bands of the homogeneous sample of 42 Seyfert 1 galaxies, that we also observed in near-IR JHK bands (Zitelli et al. 1993; Danese et al. 1992). We have applied to these data the same analysis procedure used for the infrared images, with the aim of separating the galaxian and nuclear fluxes, as well as investigating the main characteristics of the hosts. Nuclear fluxes have been estimated with typical global errors of 0.15 mag, while 0.3 mag errors are on average associated to host galaxy magnitudes. It is shown that in half of the host galaxies the bulge contribute more than 40% to the total observed fluxes even within small apertures. In the sample galaxies disks are dominating over the bulge in the large majority of the cases, suggesting that a significant fraction of Seyfert galaxies could be late-type spirals. Moreover the galactic morphological parameters are in the ranges of typical spiral galaxies. The statistics of galactic colors show that the host galaxies tend to be bluer than the normal ones. This fact added to redder colors found in the IR-bands strengthens the suggestion that in Seyfert galaxies the star formation is on average enhanced.