The present sample was extracted from a list of probable binary galaxies determined through the use of a density enhancement criteria applied to the ESO-LV catalog (Soares et al. 1995). Our radial velocity measurements of this sample reveal that about 70% of the originally selected pairs are actually true binary systems. The sample contains a large fraction of pairs with separations larger than 100 kpc and therefore can be useful to constrains the mass-to-light ratio since their mean separation is probably larger than the extent of their individual halos. It is our goal to measure more radial velocities in order to focus on that subject.
A comparison of the flux calibrated spectra with those of field ellipticals,
used as template for old stellar population, shows that ellipticals in pairs
tend to have a contribution 
of young stellar population.
This result suggest that even the small interaction between galaxies
belonging to loose pairs may be sufficient to increase the mean star
formation rate at the required level. If large gaseous halos similar to the
one reported by Hoffman et al. (1992) are a common feature
among normal galaxies, then it may be possible that the small tidal field in
loose pairs would be enough to disturb these halos that will become unstable
and will increase the star formation rate. There is no correlation of the
indicator of contribution of young stellar contribution with the projected
pair separation, in agreement with CO observations.
Acknowledgements
We thank the referee P. Prugniel for helpful comments and useful suggestions. We are grateful to CTIO for the telescope time allocated to this project. We also acknowledge to CNPq and FAPESP for partial finnancial support to this project.