EDP Sciences
Free access
Volume 384, Number 3, March IV 2002
Page(s) 780 - 792
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20020066

A&A 384, 780-792 (2002)
DOI: 10.1051/0004-6361:20020066

Multicolor photometry of ten Seyfert 1 galaxies

N. V. Boris1, C. J. Donzelli1, M. G. Pastoriza2, A. Rodriguez-Ardila3 and D. L. Ferreiro1

1  IATE, Observatorio Astronómico, Universidad Nacional de Córdoba, Laprida 854, 5000, Córdoba, Argentina
2  Departamento de Astronomia - UFRGS. Av. Bento Gonçalves 9500, CEP 91501-970, Porto Alegre, RS, Brazil
3  Instituto Astronômico e Geofísico - Universidade de São Paulo, Av. Miguel Stefano 4200, CEP 04301-904, São Paulo, SP, Brazil

(Received 6 September 2001 / Accepted 7 December 2001 )

We present new valuable BVI photometry of ten Seyfert 1 galaxies and narrow band H $\alpha$ images for six of these objects. The results indicate that the distribution of the luminosity of the sample has an amplitude of almost 4 mag with an average of MB=-20.7. The observed morphologies are confined to early type galaxies. A barred structure is found in only 2 objects. Despite that early morphological types are dominant in this sample, integrated ( B-V) colors are very blue. For instance, the SO galaxies show, on average, a (B-V)=0.78. This effect seems to be caused by the luminosity contribution of the active nucleus and/or the disk to the total luminosity of the galaxy. In the B band, the contribution of the active galactic nucleus to the total luminosity of the galaxy varies from 3% to almost 60% and the bulge to disk luminosity ratio ( $L_{\rm bulge}/L_{\rm disk}$) ranges from 0.6 to 22. Signs of tidal interactions seem to be a common characteristic since they are observed in 6 of the objects and one of them seems to be located in a poor cluster not yet identified in the literature. In contrast, H $\alpha$ extended emission is rare, with only 1 galaxy showing clear evidence of it. Luminosity profile decomposition shows that the model Gauss + bulge + disk properly reproduces the surface brightness of the galaxies. However, in order to account for the luminosity profile, most of the disk galaxies need the inner truncated exponential form with a central cutoff radius ranging from 3 to 10 kpc. This is interpreted in terms of reddened regions that are well identified in the B-V color maps. These regions present very similar colors among them, with $(B-V)\sim1.2$. This fact could be associated with the presence of dust confined in the inner regions of the galaxies.

Key words: galaxies: photometry -- galaxies: active -- galaxies: Seyfert

Offprint request: C. J. Donzelli, charly@oac.uncor.edu

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© ESO 2002