We present the discovery of a white dwarf companion at \sim 3.6 ^ { \prime \prime } from GJ 3346 , a nearby ( \pi \sim 42 mas ) K star observed with SPHERE @ VLT as part of an open time survey for faint companions to objects with significant proper motion discrepancies ( \Delta \mu ) between Gaia DR1 and Tycho-2 .
Syrius-like systems like GJ 3346 AB , which include a main sequence star and a white dwarf , can be difficult to detect because of the intrinsic faintness of the latter .
They have , however , been found to be common contaminants for direct imaging searches .
White dwarfs have in fact similar brightness to sub-stellar companions in the infrared , while being much brighter in the visible bands like those used by Gaia .
Combining our observations with Gaia DR2 and with several additional archival data sets , we were able to fully constrain the physical properties of GJ 3346 B , such as its effective temperature ( 11 \times 10 ^ { 3 } \pm 500 K ) as well as the cooling age of the system ( 648 \pm 58 Myrs ) .
This allowed us to better understand the system history and to partially explains the discrepancies previously noted in the age indicators for this objects .
Although further investigation is still needed , it seems that GJ 3346 , which was previously classified as young , is in fact most likely to be older than 4 Gyrs .
Finally , given that the mass ( 0.58 \pm 0.01 M _ { \odot } ) and separation ( 85 au ) of GJ 3346 B are compatible with the observed \Delta \mu , this discovery represents a further confirmation of the potential of this kind of dynamical signatures as selection methods for direct imaging surveys targeting faint , sub-stellar companions .