  Radial velocity planet search surveys of nearby Solar-type stars have shown a
strong deficit of brown dwarf companions within $\sim5\,\mathrm{AU}$. There is
presently no comprehensive explanation of this lack of brown dwarf companions,
therefore, increasing the sample of such objects is crucial to understand their
formation and evolution. Based on precise radial velocities obtained using the
SOPHIE spectrograph at Observatoire de Haute-Provence we characterise the
orbital parameters of $15$ companions to solar-type stars and constrain their
true mass using astrometric data from the Hipparcos space mission. The nine
companions not shown to be stellar in nature have minimum masses ranging from
~$13$ to $70\,\mathrm{M}_{\mathrm{Jup}}$, and are well distributed across the
planet/brown dwarf mass regime, making them an important contribution to the
known population of massive companions around solar-type stars. We characterise
six companions as stellar in nature with masses ranging from a minimum mass of
$76 \pm 4\,\mathrm{M}_{\mathrm{Jup}}$ to a mass of $0.35 \pm
0.03\,\mathrm{M_\odot}$. The orbital parameters of two previously known
sub-stellar candidates are improved.
