The mass distribution within our Galaxy - A three component model

Existing Galactic structure information is used in the selection of a range of models that are probably in agreement with the true, gross large-scale structure of the Galaxy out of a set of mass distribution models in which the relative predominance of the dark corona is parametrized by the escape velocity at the sun. The method employed is objective in that no assumed mass-to-light ratios are used. Results are derived from a minimization of chi-squared, given known kinematical measurements and their estimated associated errors. In the best model, the solar radius is 9.1 + or - 0.6 kpc, the local disk surface density is 82 + or - 12 solar masses/sq pc, the local circular velocity is 243 + or - 20 km/sec, and the local escape velocity is in the range of 550-650 km/sec. A surprising result is that, at the solar radius, the density of matter in the spheroidal component is 0.0011 solar masses/cu pc. This figure is much greater than that found by Schmidt (1975) from an analysis of observed high-velocity stars.