5 Conclusions

In order to analyze the photometrical signature of gravitational interactions in spiral galaxies, we present results of our BVRI surface photometry for a first set of 33 (S+S) pairs from the Karachentsev (1972) catalogue. We show that our derived parameters are generally in good agreement with those reported in RC3, aperture photometry catalogues and other individual photometric works. In addition, we present multiaperture photometry in order to facilitate further comparisons and contribute to the existing database of aperture photometry. The combination of 2D (B-I) colour maps and sharp/filtered B images appears to be a powerful technique both for morphological classification and for revealing fine structural details most likely related to encounters that are in various early and late stages. There is a tendency of barred galaxies to show grand design morphologies and flat colour profiles. In general our data suggest that our sample is undergoing moderate interactions which appear to be adequate to stimulate a nonaxisymmetric potential that generate a global response as evidenced by the presence of bars, rings, pseudo-rings and knotty structures along the arms and disks of the spiral galaxies in (S+S) pairs.

Acknowledgements

I.P. thanks the staff of the Observatorio Guillermo Haro for the help in the observations and also likes to thank E. Athanassoula for interesting discussions on spiral structure. These discussions were made possible via the ECOS/ANNUIES exchange project M99-U02, for which we are thankful. H.H.T. thanks J. Sulentic for his valuable comments. H.H.T. and I.P. thank the referee Dr. R. Rampazzo for his careful reading of this manuscript. His constructive criticism has helped us to clarify and focus our paper enormously.