The mass density in our galaxy. I. A dynamical model constrained by general star counts

The authors attempt to model stellar populations in the galactic disc so as to get self-consistent solutions of the Boltzmann and Poisson equations. The contributions of the interstellar matter, corona, bulge and a possible unseen-mass disc are added. The corona and bulge parameters are adjusted until the potential produces an acceptable rotation curve. The density laws obtained can be translated in terms of star count predictions. The authors obtain a dynamical mass density in the solar neighbourhood in the range 0.09 to 0.12 M_sun; pc^-3. This value is well compatible with published estimations of the observed local mass. It is found that the local missing mass, if any, does not exceed 0.03 M_sun; pc^-3. The best fit is obtained for an unseen mass disc with 0.01 M_sun; pc^-3 density and 600 pc scale height. A flattening of the dark corona would produce the same effect.