We report the discovery of a 16–20 M _ { \mathrm { Jup } } radial velocity companion around the very young ( \sim 3 Myr ) brown dwarf candidate Cha H \alpha 8 ( M5.75–M6.5 ) .
Based on high-resolution echelle spectra of Cha H \alpha 8 taken between 2000 and 2007 with UVES at the VLT , a companion was detected through RV variability with a semi-amplitude of 1.6 km s ^ { -1 } .
A Kepler fit to the data yields an orbital period of the companion of 1590 days and an eccentricity of e =0.49 .
A companion minimum mass M _ { 2 } \sin i between 16 and 20 M _ { \mathrm { Jup } } is derived when using model-dependent mass estimates for the primary .
The mass ratio q \equiv M _ { 2 } / M _ { 1 } might be as small as 0.2 and , with a probability of 87 % , it is less than 0.4 .
Cha H \alpha 8 harbors most certainly the lowest mass companion detected so far in a close ( \sim 1 AU ) orbit around a brown dwarf or very low-mass star .
From the uncertainty in the orbit solution , it can not completely be ruled out that the companion has a mass in the planetary regime .
Its discovery is in any case an important step towards RV planet detections around BDs .
Further , Cha H \alpha 8 is the fourth known spectroscopic brown dwarf or very low-mass binary system with an RV orbit solution and the second known very young one .