  Brown dwarfs are intermediate objects between planets and stars. The lower
end of the brown-dwarf mass range overlaps with the one of massive planets and
therefore the distinction between planets and brown-dwarf companions may
require to trace the individual formation process. We present results on new
potential brown-dwarf companions of Sun-like stars, which were discovered using
CORALIE radial-velocity measurements. By combining the spectroscopic orbits and
Hipparcos astrometric measurements, we have determined the orbit inclinations
and therefore the companion masses for many of these systems. This has revealed
a mass range between 25 and 45 Jupiter masses almost void of objects,
suggesting a possible dividing line between massive planets and sub-stellar
companions.
