Kinematics of the Open Cluster System in the Galaxy

Absolute proper motions and radial velocities of 202 open clusters in the solar neighborhood, which can be used as tracers of the Galactic disk, are used to investigate the kinematics of the Galaxy in the solar vicinity, including the mean heliocentric velocity components (u,u,u) of the open cluster system, the characteristic velocity dispersions (σ,σ,σ), Oort constants (A, B) and the large-scale radial motion parameters (C,D) of the Galaxy. The results derived from the observational data of proper motions and radial velocities of a subgroup of 117 thin disk young open clusters by means of a maximum likelihood algorithm are: (u,u2,u3) = (-16.1±1.0, -7.9±1.4,-10.4±1.5) kms, (σ,σ,σ) = (17.0 ±0.7,12.2±0.9,8.0±1.3) kms,(A,B) = (14.8±1.0,-13.0±2.7) kmskpc,and(C,D) = (1.5±0.7,-1.2±1.5) kmskpc. A discussion on the results and comparisons with what was obtained by other authors is given.