PATTERN SPEED DOMAINS IN RINGED DISK GALAXIES FROM OBSERVATIONAL AND SIMULATIONAL DATABASES

New test-particle simulations have been carried out to learn more abou t the secular, evolution and morphology of the gaseous and stellar dis tributions in barred galaxies. We verify the previous results Of P. Sc hwarz that gas clouds will tend to collect into ring-like patterns nea r major orbit resonances, owing to gravity torques. However, we improv e on these results in several ways. Firstly, we use more gas clouds (1 0 000 vs 2000) than Schwarz and track individual clouds to determine w hen they collide, rather than using a collision box as did Schwarz. Se condly, besides Schwarz's isochrone rotation curve, we also use a flat rotation curve. Thirdly, we consider more bar pattern speeds and stre ngths than did Schwarz. Finally, unlike Schwarz and other simulators, we have a large database of images and color index maps of nearly 140 ringed galaxies that can be compared to the simulations to evaluate th eir significance. We confirm the two types of outer Lindblad resonance rings that Schwarz discovered, but find that their existence is not d ue so much to the initial density distribution of gas clouds as to pat tern speed and the time interval since the bar potential was imposed. The simulations and the images lead us to suggest that we can divide b arred galaxies according to the resonances which the bar pattern speed and rotation curve allow in the disk. We illustrate specific galaxies that we believe belong to fast, medium, and slow bar pattern speed '' domains'' and match them to particular simulation frames. We also disc uss alternative hypotheses in which the pattern speed is such that all resonances are present but the gas has been depleted or was distribut ed differently in various galaxies to produce the three classification domains.