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. 
S.A. Khoperskov, A.V. Khoperskov, I.S. Khrykin, V.I. Korchagin, D.I.   Casetti-Dinescu, T. Girard, W. van Altena, D. Maitra
astro-ph.CO astro-ph.GA