On Utmost Multiplicity of Hierarchical Stellar Systems

According to theoretical considerations, multiplicity of hierarchical stellar systems can reach, depending on masses and orbital parameters, several hundred, while observational data confirm the existence of at most septuple (seven-component) systems. In this study, we cross-match the stellar systems of very high multiplicity (six and more components) in modern catalogues of visual double and multiple stars to find among them the candidates to hierarchical systems. After cross-matching the catalogues of closer binaries (eclipsing, spectroscopic, etc.), some of their components were found to be binary/multiple themselves, what increases the system's degree of multiplicity. Optical pairs, known from literature or filtered by the authors, were flagged and excluded from the statistics. We compiled a list of hierarchical systems with potentially very high multiplicity that contains ten objects. Their multiplicity does not exceed 12, and we discuss a number of ways to explain the lack of extremely high multiplicity systems.

Dynamic study of possible host stars for extrasolar planetary systems

We present the stellar systems which consist of double and multiple stars with distances 3.5 ÷ 25 pc from the Sun, belonging to spectral classes F, G, K, M, having masses from 0.3 to 1.5 solar mass and can, in principle, possess planetary systems. On the basis of observations with Pulkovo 65 cm refractor the relative positions of double stars, the parameters of motion, the orbits and also the ephemeris for the nearest epochs have been computed.