摘要：We found that multi-periodic low-mass stars discovered by Kepler K2 in the Upper Scorpius association are closebinaries with typical separations of the order of 10 au and large mass ratios. These stars were surveyed by speckleinterferometry at the SOAR telescope with spatial resolution of 0 04. Out of 129 observed targets, we resolved70 pairs (including 16 previously known ones and three new triple systems). The distribution of projectedseparations of binaries with primary stars less massive than the Sun corresponds to a log-normal with median of11.6 au and logarithmic dispersion of 0.60 dex, similar to M dwarfs in the field. Future orbits of newly discoveredbinaries will provide accurate measurements of masses to calibrate pre-main-sequence evolutionary tracks; atentative orbit of one previously known binary is determined here.
