Method of evaluation of the most probable mean radial velocities of open star clusters

Abstract

In this article the method of self-consistent estimate of star clusters' average radial velocity by kinematic parameters was proposed. The method is based on convergent point method of probable cluster members determination. By modelling the method validation was held and properties of received estimate depending on a number of cluster parameters were explored. It was shown that the main limitation on the method applicability was imposed by cluster angular radius, which must be greater than 20 arcmin. The expected number of known clusters to which the method can be applied exceed 200. The method was applied to estimate radial velocities of several nearby open clusters with number of probable members greater than 100. For comparison purposes for these clusters the independent estimate of average and median radial velocities of probable members according to Gaia DR3 was obtained. Also the comparison with other authors' results was held. It was shown that star clusters' radial velocity estimates made by different methods are close and with insufficient number of radial velocities determinations for cluster members the proposed method gives stable estimate.