moving cluster

A moving cluster is a group of stars dynamically associated so that they have a common motion with respect to the local standard of rest. Nearby examples of moving clusters include the Hyades and the Ursa Major Moving Group. Because of perspective, the proper motions of the component stars appear to converge on a single point in the sky. If the linear velocity of the cluster is known from observations of radial velocity, then the distance of each star can be estimated from the total proper motion; this method is known as moving cluster parallax.