Tidally-triggered disk thickening. II. Results and interpretations

We have reported in a previous paper (AAS 116, 417, 1996) B, V and I band photometric data for a sample of 24 edge-on interacting spiral galaxies, together with a control sample of 7 edge-on isolated galaxies. We discuss here the main result found in this study: the ratio h/z of the radial exponential scalelength h to the constant scaleheight z is about twice smaller for interacting galaxies. This is found to be due both to a thickening of the plane, and to a radial stripping or shrinking of the stellar disk. If we believe that any galaxy experienced a tidal interaction in the past, we must conclude that continuous gas accretion and subsequent star formation can bring back the ratio h/z to higher values, in a time scale of 1 Gyr.