  We present a ~6.5'x8' Expanded Very Large Array (EVLA) mosaic observations of
the NH3 (1,1) emission in the Barnard 5 region in Perseus, with an angular
resolution of 6". This map covers the coherent region, where the dense gas
presents subsonic non-thermal motions (as seen from single dish observations
with the Green Bank Telescope, GBT). The combined EVLA and GBT observations
reveal, for the first time, a striking filamentary structure (20" wide or 5,000
AU at the distance of Perseus) in this low-mass star forming region. The
integrated intensity profile of this structure is consistent with models of an
isothermal filament in hydrostatic equilibrium. The observed separation between
the B5-IRS1 young stellar object (YSO), in the central region of the core, and
the northern starless condensation matches the Jeans length of the dense gas.
This suggests that the dense gas in the coherent region is fragmenting. The
region observed displays a narrow velocity dispersion, where most of the gas
shows evidence for subsonic turbulence, and where little spatial variations are
present. It is only close to the YSO where an increase in the velocity
dispersion is found, but still displaying subsonic non-thermal motions
