GAS-FLOW IN A 2-COMPONENT GALACTIC DISK

Numerical simulations of two-component (stars + gas) self-gravitating galactic disks show that the interstellar gas can significantly affect the dynamical evolution of the disk even if its mass fraction (relati ve to the total galaxy mass) is as low as several percent. Aided by ef ficient energy dissipation, the gas becomes gravitationally unstable o n local scale and forms massive clumps. Gravitational scattering of st ars by these clumps leads to suppression of bar instability usually se en in heavy stellar disks. In this case, gas inflow towards the galact ic center is driven by dynamical friction which gas clumps suffer inst ead of bar forcing.