  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 ~ 8%, bar strength increases (by >~ 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.
