On the kinematics of O and B stars

The radial velocities of 1018 O and B stars, Cepheid variables, and open star clusters are analyzed to determine whether the Galaxy exhibits an expansion radially outward with speed proportional to distance from the galactic center. A global solution with all the relevant parameters solved for simultaneously is obtained, and a value for the projected distance (R) from the sun to the galactic center is determined from the kinematics. The discrepant values of R are examined which would be obtained if the standard methods of Feast and Shuttleworth (1965) and Trumpler and Weaver (1953) were applied to the velocity field of the preferred solution. It is found that the data are inconsistent with the hypothesis that the local compression of the velocity field indicated by proper motions and radial velocities is due to a global expansion of the Galaxy with expansion speed decreasing with increasing galactocentric distance. The results are shown to be consistent with the density-wave model.