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 2,300 stars in multiple systems,
about 1,300 of them being UCDs out of the original 16,500 sample. Among the companions,
there are several tens of young stellar objects and white dwarfs, but also new M7-L2
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 characterization
of higher mass companions.
