  We present the analysis of MOA-2007-BLG-197Lb, the first brown dwarf
companion to a Sun-like star detected through gravitational microlensing. The
event was alerted and followed-up photometrically by a network of telescopes
from the PLANET, MOA, and uFUN collaborations, and observed at high angular
resolution using the NaCo instrument at the VLT. From the modelling of the
microlensing light curve, we derived the binary lens separation in Einstein
radius units (s~1.13) and a mass ratio of (4.732+/-0.020)x10^{-2}. Annual
parallax, lens orbital motion and finite source effects were included in the
models. To recover the lens system's physical parameters, we combined the
resulting light curve best-fit parameters with (J,H,Ks) magnitudes obtained
with VLT NaCo and calibrated using IRSF and 2MASS data. We derived a lens total
mass of 0.86+/-0.04 Msun and a lens distance of 4.2+/-0.3 kpc. We find that the
companion of MOA-2007-BLG-197L is a brown dwarf of 41+/-2 Mjup observed at a
projected separation of 4.3+/-0.1 AU, and orbits a 0.82+/-0.04 Msun G-K dwarf
star. We study the statistical properties of this population of brown dwarfs
detected by microlensing, transit, radial velocity, and direct imaging (most of
these objects orbit solar-type stars), and we performed a two-dimensional,
non-parametric probability density distribution fit to the data, which draws a
structured brown dwarf landscape. We confirm the existence of a region that is
strongly depleted in objects at short periods and intermediate masses (P<30 d,
M~30-60 Mjup), but also find an accumulation of objects around P~500 d and M~20
Mjup, as well as another depletion region at long orbital periods (P>500 d) and
high masses (M>50 Mjup). While these data provide important clues on mechanisms
of brown dwarfs formation, more data are needed to establish their relative
importance, in particular as a function of host star mass.
