MSC - A catalogue of physical multiple stars

The MSC catalogue contains data on 612 physical multiple stars of multiplicity 3 to 7 which are hierarchical with few exceptions. Orbital periods, angular separations and mass ratios are estimated for each subsystem. Orbital elements are given when available. The catalogue can be accessed through CDS (Strasbourg). Half of the systems are within 100 pc from the Sun. The comparison of the periods of close and wide sub-systems reveals that there is no preferred period ratio and all possible combinations of periods are found. The distribution of the logarithms of short periods is bimodal, probably due to observational selection. In 82% of triple stars the close subsystem is related to the primary of a wide pair. However, the analysis of mass ratio distribution gives some support to the idea that component masses are independently selected from the Salpeter mass function. Orbits of wide and close sub-systems are not always coplanar, although the corresponding orbital angular momentum vectors do show a weak tendency of alignment. Some observational programs based on the MSC are suggested.