Mass determination of open clusters using kinematics data

Abstract

We estimate the mass of three open clusters, NGC 2168, NGC 188, NGC 6819, using kinematics data of open cluster stars member. Radial velocity data determined from WIYN survey and proper motion determined from Gaia DR2. Using virial theorem and projected-mass estimator method we estimate the mass of star open clusters. Both methods give a reasonable result for all clusters mass. The accuracy of estimated mass affected by some parameters such as membership probability of stars sample, the distance, age, and angular radius of open clusters. We estimate the mass of clusters within a central radius of the cluster. The mass of open clusters using virial theorem is 4056 M⊙ (d < 7 pc) for NGC 2168, 2776 M⊙ (d < 8 pc) for NGC 188, and 4244 M⊙ (d < 1.6 pc) for NGC 6819. Using projected mass estimator we get 5833 M⊙ (d < 7 pc) for NGC 2168, 3326 M⊙ (d < 8pc) for NGC 188, and 3518 M⊙ (d < 1.6pc) for NGC 6819.