Global Gravitationally-Organized Spiral Waves and the Structure of NGC
  5247
  Using observational data, we build numerical N-body, hydrodynamical and
combined equilibrium models for the spiral galaxy NGC 5247. The models turn out
to be unstable towards spiral structure formation. We simulate scenarios of
spiral structure formation for different sets of equilibrium rotation curves,
radial velocity dispersion profiles and disk thickness and demonstrate that in
all cases a simulated spiral pattern qualitatively agrees with the observed
morphology of NGC 5247. We also demonstrate that an admixture of a gaseous
component with mass of about a few percent of the total mass of the disk
increases a lifetime of a spiral pattern by approximately 30%. The simulated
spiral pattern in this case lasts for about 3 Gyr from the beginning of the
growth of perturbations.
