ON THE MULTIPLICITY OF SPECTROSCOPIC BINARY STARS

The frequency of systems of multiplicity 3 or higher among the spectro scopic binary stars, in which the primary component is a dwarf of mass between 0.5 and 1.5 solar masses, depends sensitively on the binary's orbital period: for periods shorter than 10 days, this frequency is n o less than 40%, while for periods between 10 and 100 days, it is a fa ctor of 2 or 3 lower. This result has been obtained by comparing the c atalog of orbits of spectroscopic binaries with the catalog of multipl e systems and is confirmed by samples of dwarfs in the solar neighborh ood that have been studied most thoroughly. Our observations also show that the frequency of spectroscopic binaries with periods up to 100 d ays among the distant faint third components in well-known multiple sy stems is a factor of 2 or 3 higher than that among the held stars. It is suggested that the presence of distant components plays a major rol e in forming close pairs.