Ultra-cool dwarfs (UCDs) serve as a link between the lowest mass stars and the brown
dwarfs. Gaia DR2 revealed thousands of ultra-cool dwarfs not identified as such before.
In this work, we searched for companions to those in the Gaia catalogue, from their
common proper motions and parallaxes. We found about 1,700 stars in multiple systems
out of the original 16,500 sample. Among the companions, there are several tens of
young stellar objects and white dwarfs, but also new UCD candidates. Such a sample
can be used to better understand the binary properties of UCDs and to better characterize
the physics of UCDs thanks to the easier characterization of higher mass companions.
