Stability of two-fluid galactic disc under the influence of an external
  tidal field
  We consider the dynamics of rotationally supported thin galactic disc
composed of stars and gas under the influence of external tidal field and
derive the coupled differential equations governing the evolution of
instabilities. Further linearising the governing equation a modified dispersion
relation and stability criterion for appraising the stability of the two fluid
galactic disc under the influence of external tidal field is obtained. Possible
applications and method for the same are discussed.
