A força perpendicular ao plano galactico e a distribuição de massa na zona local

Abstract

The component of the galactic gravitational Field perpendicular to the galactic plane, in the neighbourhood of the Sun, is obtained though unidimensional integration of Possions equation. The result agrees with limits calculated by Quiroga (1980) and does not essentially differ from classic results (Wooley, 1957; Oort, 1960). Nevertheless it indicates that the galactic disk is somewhat narrower than has been supposed. The mass density un the local zone is calculated with a dynamic method similar to that introduced by Oort (1932). A term usually neglected in the hydrodynamic equation is evaluated and probably such a term is responsible for the overestimated local density. The final result of 0,11 0,12 M0/pc³ agrees with the density value obtained by direct observation.The density distribution in the direction perpendicular to the galactic plane is postulated from recent observation data concerning KM stars (Upgren, 1978; Upgren et al., 1981). This stellar group is satisfactory ly representative for of the Galaxy as a whole in terms of mass population is determined directly from observations; an observational program is proposed.