ON THE POSSIBILITY OF RECONSTRUCTING THE PHASE DENSITY FOR STAR-CLUSTERS

We propose a method for reconstructing the phase density (distribution function) of stars in open and globular clusters based on the solutio n of integral equations from stellar radial-velocity and proper-motion data. The phase density is the most complete characteristic of kinema tic and dynamical properties of clusters and the determination of even its main features makes it possible to point out the principal relaxa tion process that occurred in the cluster under study. We discuss vari ous methods for extracting information on the character of the phase d istribution of stars, in particular, for inferring the velocity anisot ropy, from observational data. It is shown that the accuracy of modern measurements of relative proper motions (0.0005-0.001 '' arcsec yr(-1 )) and that of correlation radial-velocity measurement methods, which is substantially better than 1 km s(-1), are sufficient for this purpo se.