On efficiency of kinematic methods for membership determination of open clusters with small proper motions.
The membership determination errors, inherent in some known kinematic methods, used for separation of field stars and cluster members, are discussed. An error analysis has been carried out by means of simulation of real star distribution in the vicinity of two open clusters - their proper motions, angular coordinates and visual magnitudes. It has been shown that, depending on the method applied and on characteristics of star distribution, the separation can lead to losses of up to Sc = 10 - 60% of the total number of cluster members n. Simultaneously up to SΦ = 0.1n - 2n field stars can be erroneously included in the list of cluster members. A method allowing both for kinematic data and visual magnitudes V or V0 distribution has minimum errors Sc = (0.1 - 0.4)n, SΦ = (0.1 - 0.2)n, and is especially suitable for identification of bright stars. For clusters with small proper motions none of the known methods allows to obtain reliable lists of members on the error level of Sc+SΦ < 0.1n.
Kinematika i Fizika Nebesnykh Tel
- Pub Date:
- Open Clusters;
- Star Distribution;
- Stellar Motions;
- Angular Distribution;
- Stellar Models;