The morphology of the outer rings of early-type spiral galaxies is compared to integrations of massless collisionless particles initially in nearly circular orbits .
Particles are perturbed by a quadrupolar gravitational potential corresponding to a growing and secularly evolving bar .
We find that outer rings with R1R2 morphology and pseudorings are exhibited by the simulations even though they lack gaseous dissipation .
Simulations with stronger bars form pseudorings earlier and more quickly than those with weaker bars .
We find that the R1 ring , perpendicular to the bar , is fragile and dissolves after a few bar rotation periods if the bar pattern speed increases by more than \sim 8 \% , bar strength increases ( by \ga 140 \% ) after bar growth , or the bar is too strong ( Q _ { T } > 0.3 ) .
If the bar slows down after formation , pseudoring morphology persists and the R2 ring perpendicular to the bar is populated due to resonance capture .
The R2 ring remains misaligned with the bar and increases in ellipticity as the bar slows down .
The R2 ring becomes scalloped and does not resemble any ringed galaxies if the bar slows down more than 3.5 % suggesting that bars decrease in strength before they slow down this much .
We compare the morphology of our simulations to B-band images of 9 ringed galaxies from the Ohio State University Bright Spiral Galaxy Survey , and we find a reasonable match in morphologies to R1R2 ’ pseudorings seen within a few bar rotation periods of bar formation .
Some of the features previously interpreted in terms of dissipative models may be due to transient structure associated with recent bar growth and evolution .