COUNTER-ROTATING BARS WITHIN BARS

The dynamical stability and evolution of disc galaxies with different disc thickness as well as various fraction and concentration of stella r counter-rotation is investigated with self-consistent numerical simu lations. In particular, systems of nested, counter-rotating, stable ba rs are presented. As for the direct case, the nuclear secondary bar ro tates faster than the primary bar. Contrary to the direct case, the pr esence of significant amount of gas is not necessary to produce such s ystem. Observed bars within bars in lenticular (i.e. gas-poor) galaxie s could thus be explained by counter-rotating bars. This hypothesis ca n easily be tested since the retrograde case produces distinct kinemat ical signatures from the direct one. Moreover, the best morphological similarities between numerical models and typical SB0's are found in t he models with significant amount of stellar nuclear counter-rotation.