  We present imaging and spectroscopic observations with HST (WFPC2, ACS/HRC
and STIS), VLT (FORS2) and Keck (HIRES) of the dM8 ultra-cool dwarf DENIS-P
J185950.9-370632, located in the R-CrA region. The presence of lithium
absorption at 670.8 nm and the strong Halpha emission indicate a young age and
a sub-stellar mass. Our diffraction-limited images resolve a companion at the
separation limit of HST/ACS (~0.06"). The 2.1 mJy flux in the LW2 filter
(5.0-8.5 microns) of the Infrared Space Observatory (see 1999A&A...350..883)
likely corresponds to an infrared excess, suggesting the presence of
circumstellar material. Proper motion and photometric measurements, as well as
the Halpha activity, confirm membership in the R-CrA star forming region. If
confirmed by further observations, DENIS-P J185950.9-370632 would be the first
accreting sub-stellar multiple system observed to date.

Astrophysics