A Search for Substellar Companions to Low-Mass Stars

Multiple, precise Doppler measurements (+ or - 230 m/s) are presented for a sample of 70 low-mass stars in order to search for weak gravitational perturbations due to brown dwarf companions. The measurements make it possible to detect companions with masses greater than 0.007 solar mass and orbital periods less than 4 yrs. It is found that six of the considered stars have stellar companions. However, none of the stars have substellar companions. It is concluded that although several brown dwarf candidates exists, there is no convincing detection of an object with a mass significantly below 0.08 solar mass.