6 Conclusions

We presented the kinematics of the stellar and gaseous components in 51 galaxies. The sample is composed of 5 elliptical galaxies in the G93, considered spectro-photometric template in Paper I, 21 shell galaxies (22 nuclei) and 30 pair members. With the exclusion of RR 24b, all the galaxies have morphological type T<0. Galaxies in the sample are located in low density environments and most of pair members show fine structures reported in Paper I.

The systemic velocity and central velocity dispersion characterizing the stellar kinematics of the more luminous galaxies in the sample are in good agreement with previous investigations, with few exceptions. A remarkable one concerns E 2400100 whose spectrum shows two distinct nuclei, not previously noticed, embedded in the main body of the galaxy. The shape of the composite velocity profile this galaxy may be interpreted in the framework of the U-shape profiles discussed by Combes et al. (1995).

$V/\sigma$ as a function of radius shows a manifold of trends in the central parts of the shell galaxies. If shell galaxies have suffered a merging according to Heyl et al. (1996) we should find basically random motion in the center and rotation in the outskirts, since a significant outward angular momentum transfer is foreseen during a merging process. The manifold of trends noticed suggest that different mechanisms could be involved in the shells formation.

A small fraction of the objects show emission lines; in few of them, most of which are pair members, gas emission is extended. None of the objects in the sample shows counter-rotation of the gaseous versus the stellar component. On the contrary, we found cases in which the two components are associated. In two cases there is evidence that gas and stars lie on different planes. This latter phenomenon could be associated to accretion events.

From the ratio ([O II]/H$\beta$) we deduce that the physical condition of the gas in RR 331a is typical of a Seyfert. A double component visible in the line profile in the nucleus further supports this hypothesis which needs to be confirmed using wider spectral ranges. Evidence about the presence of a LINER nucleus in 4 galaxies belonging to the shells sample has been addressed using ([N II]/ H$\alpha$) emission lines ratio obtained by Phillips et al. (1986). It remains unexplained what are the mechanism/s generating the LINER activity (e.g. shoch waves, starburst, HII region plus a low level nuclear activity, etc.). Other shell galaxies showing ([O II] $\lambda$ 5007) could be in the regime of normal HII regions or belong to a a class of "transition'' objects (as defined by Ho 1996), which lie in between HII regions and LINERS: a larger spectral range is necessary in order to classify them. From the line profile we have not indication of the presence of a broad component, which can be directly linked to the classical Seyfert galaxy type or to any kind of nuclear activity.

Acknowledgements

We wish to thank Francois Simien who permitted us to use his Fourier Fitting package and Daniela Bettoni and Giuseppe Galletta for tests made with their FQ package. ML acknowledges the kind hospitality of the Brera Observatory and of the Padova Observatory during her PhD Thesis. ML, AB and CC acknowledge the support by the European Community under TMR grant ERBFMRX-CT96-0086.