ИСТИНА

Since the star formation in galaxies is determined by the amount of molecular hydrogen, and the formation of molecules is associated with gas pressure, it is important to analyse the radial dependence of the molecular gas density, as well as to investigate the fraction of molecular gas \eta=\Sigma_H2/\Sigma_HI depending on the gas pressure P. We construct the self-consistent model of an axisymmetric disc with finite thickness in a gravitational field of dark halo taking into account a self-gravitation of gas and stars in order to get volume density of components and gas pressure. The galaxies inside and outside of Virgo cluster have been compared in order to study the influence of the environment on interstellar medium. Possible reasons for the unusual behaviour of Virgo galaxies sample on the plot \eta(P) is discussed.