Assessing the disk galaxy stability through the time

N-body simulations have shown that the bar can be triggered by two processes: (1) by own instabilities in the disk, or (2) by interactions with other galaxies. Both mechanisms have been widely studied. However, the literature has not shown measurements of the critical limits of the Disk Stability Parameters, DSP. We showed measurements of those parameters through whole evolution in isolated disk models finding that the initial rotation configuration of those models is saved in the stable or unstable regimen from the initial to the final evolution. Then, we perturbed such isolated models to study the evolution of DSP under perturbation. We find that the critical limits of DSP are not much affected in barred models, however, when the bar is triggered by the perturbation, the disk fall in the unstable regimen. We show in our models that the bar triggered by a light perturbation grows into two phases: first, the bar appears as slow rotator, then it evolves toward fast rotator; second, when the perturbation is far from the target galaxy, the bar evolves from fast to slow rotator. Nevertheless, when the bar is triggered by a heavy perturbation, it appears as fast rotator and evolves toward slow rotator similar to classical bar models.