Title: Spectroscopic companions to very young brown dwarfs
Author: Viki Joergens (Sterrewacht Leiden)

Multiplicity of very young brown dwarfs is a key parameter for 
their formation. Recent results of searches for companions
to old field brown dwarfs give important insights into the 
substellar binary population at ages of a few billion years.
However, these results represent only a boundary condition, 
which need not to be matched at any earlier time.
Therefore, it is of interest for the current discussion of 
brown dwarf formation scenarios to study multiplicity at very young ages.

In this talk, results of the first RV survey for spectroscopic companions
to very young brown dwarfs and (very) low-mass stars in the ChaI 
star forming cloud with UVES at the VLT are presented.
This survey studies the binary fraction in an as yet unexplored
domain not only in terms of primary masses (substellar regime)
and ages (a few Myr) but also in terms of companion masses
(sensitive down to planetary masses) and separations (< 1AU). 
The UVES spectra obtained so far hint at spectroscopic
companions of a few Jupitermasses around one brown dwarf and around
one low-mass star (~0.2 Msol) in orbits of at least several months.
The formation of brown dwarfs and low-mass stars with close companions
is discussed in the context of currently proposed models.