In paper Melnyk & Vavilova (2006) “Galaxy triplets of the local supercluster. 3.Configuration properties”we studied the configuration properties of observed galaxy triplets using the Agekian-Anosova configuration diagram (fig.1). The examples of the observed galaxy triplets of different configurations are shown in Fig. 2.
The configuration of a galaxy triplet, i.e., the shape of the triangle formed by the galaxies, is an important characteristic of its dynamical evolution. Computer simulations of the dynamical evolution of triplet systems show that a triplet spends more than half of its lifetime in a state when two galaxies are close to one another, while the third galaxy is far from them (see for example Chernin et al. 1995 and references in Melnyk & Vavilova, 2006). This triplet configuration is called hierarchical. However, the pattern of the dark matter distribution is of great importance in the evolutionary processes of triplets. The presence of dark matter in the volume of a system accelerates the growth of a dynamical instability in it and enhanced the system’s chaotization, thereby suppressing the formation of long-lived close pairs. According to simulations the excess of hierarchical configurations in the triplet sample assumes that the dark matter is distributed in the halos of individual galaxies.