Statistical studies of visual double and multiple stars. II. A catalogue of nearby wide binary and multiple systems.

A catalogue of nearby wide double and multiple systems is presented. It contains 305 binaries, 26 triples and 3 quadruples closer to the Sun than 22.5 pc (π ≥ 0.044″ and with mutual separations larger than 25 AU. The catalogue includes updated astrometric, photometric and kinematic data, as well as information on possible membership to moving groups, and an age classification into probably young (PYS) and probably old system (POS). The basis for this list is Gliese's Catalogue of Nearby Stars, with additional information from Luyten's LDS and NLTT. The catalogue is found to be reasonably complete to absolute visual magnitude 13 in a volume of radius 13 pc. Several tests were performed in order to exclude as far as possible optical members. Among the 305 binaries 211 POS and 94 PVS were found, and among the 29 multiple systems 12 POS and 17 PYS. Space velocity dispersions have been calculated for the systems classified as probably old or young. Significant differences between both groups are found. The velocity dispersion found for the young group is σ_y(PYS) = 35.2 km s^-1, while that of the old group is σ_y(POS) = 53.7 km s^-1. The kinematic ages corresponding to these velocity dispersions are τ(PYS) = 1.9×10⁹yrs, τ(POS) = 4.6×10⁹yrs. 32 systems are probable members of the Hyades supercluster and 14 of Sirius. The intrinsic fraction of wide double and multiple stars to field stars is about 0.2 in the solar vicinity.