The molecular gas content of the Pipe Nebula I. Direct evidence of
  outflow-generated turbulence in B59?
  The Pipe Nebula is a molecular cloud hosting the B59 region as its only
active star-forming clump. While the particular importance of outflows in
active star forming regions is subject of debate, the quiet nature of the gas
in B59 makes it a good site to directly see the impact of protostellar feedback
on the quiescent dense gas. Using HARP at the JCMT, we mapped the B59 region
with the J=3-2 transition of 12CO to study the kinematics and energetics of the
outflows, and 13CO and C18O to study the overall dynamics of the ambient cloud,
the physical properties of the gas, and the hierarchical structure of the
region. The B59 region has a total of 30Msun of cold and quiescent material,
mostly gravitationally bound, with narrow line widths throughout. Such low
levels of turbulence in non-star-forming sites of B59 are indicative of the
intrinsic initial conditions of the cloud. On the other hand, close to the
forming protostars the impact of the outflows is observed as a localised
increase of both line widths from 0.3 to 1 km/s, and 13CO excitation
temperatures by 2-3K. The impact of the outflows is also evident in the low
column density material which shows signs of being pushed, shaped and carved by
the outflow bow shocks as they pierce their way out of the cloud. Much of this
structure is readily apparent in a dendrogram analysis of the cloud. The low
mass of B59 together with its intrinsically quiescent gas and small number of
protostars, allows the identification of specific regions where the outflows
from the embedded sources interact the dense gas. Our study suggests that
outflows are an important mechanism for injecting and sustaining supersonic
turbulence at sub-parsec size scales. We find that less than half of the
outflow energy is deposited as turbulent energy of the gas, however this
turbulent energy is sufficient to slow down the collapse of the region.
