CONFIGURATIONS OF TRIPLETS OF GALAXIES

Three methods of statistical study of triple systems' configurations have been proposed. The mathematical expectations of geometrical characteristics have been compared for observed and simulated triangles in the first method of configurational parameters. The deviations from true configurations due to projection effects have been considered. The other two methods employ the division of configurational diagram D into zones. In the inverse-matrix method, the true zonal statistics of configurations has been restored by solution of the set of linear equations, the right-hand sides of which are the observed numbers of configurations and the coefficients are the probabilities of zone-to-zone transitions due to projections. The method of accidental coincidences compares the statictics of observed configurations and projected ones for hypothetical catalogs. If the difference between the number of observed and projected configurations for each zone does not exceed one and the total sum of these differences over all zones in not greater than two, the hypothetical ensemble has been consiered as <<true>>. For the sample of probably physical triplets of galaxies from the Karachentseva et al.'s (1979) catalog, the predominance of configurations close to equilateral triangle has been revealed.