Comparisons of a Galactic Kinematic Model with Two Proper‐Motion Surveys in the Vicinity of the North Galactic Pole

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Abstract
A Galactic kinematic model has been constructed for modeling the distributions of magnitude, colors, and proper motions. In addition, we have developed a star-count analysis algorithm, which uses all available information to extract Galactic structure parameters in an m-dimensional space of observables. In this paper, as a first application, we compare the predicted stellar distributions with two proper-motion surveys in the four-dimensional space of observables (V, B-V, μl, μb), thus discriminating between Galactic components on the basis of their magnitude, color, and kinematic distributions. Our result favors the existence of a velocity dispersion gradient from the Galactic plane for disk and thick-disk stars. The thick disk has a scale height of 1300 pc and a local density of 2.0% of the disk, and the scale height of the old disk is found to be about 340 pc. We find that a globular cluster function at the bright end of the spheroid luminosity function with an axial ratio (c/a) of 0.8 is in good agreement with the observations.