Herschel spectral-line mapping of the HH211 protostellar system
  (Abridged) Mid- and far-infrared observations of the environment around
embedded protostars reveal a plethora of high excitation molecular and atomic
emission lines. In this work we present spectro-imaging observations of the
HH211 system with Herschel/PACS that record emission from major molecular (CO,
H2O and OH) and atomic coolants (e.g. [OI]). Molecular lines are mainly exited
at the terminal bowshocks of the outflow and around the position of the
protostar. All lines show maxima at the southeast bowshock with the exception
of water emission that peaks around the central source. Excitation analysis in
all positions shows that CO and H$_2$O are mainly thermally excited at T~ 350 K
and 90 K respectively, with the CO showing a second temperature component at
750 K towards the southeast peak. Excitation analysis breaks down in the case
of OH, indicating that the molecule is non-thermally excited. Comparisons
between the CO and H2 column densities suggest that the CO abundance value in
shocks can be up to an order of magnitude lower than the canonical value of
10$^{-4}$. The water ortho-to-para ratio around the protostar is only 0.65,
indicating low-temperature water ice formation followed by non-destructive
photodesorption from the dust grains. Therefore the low ortho-to-para ratio in
water that can be interpreted in terms of formation from a primordial gas
reservoir in the protostellar envelope. The two-sided total atomic mass flux
estimated from the [OI] jet sums to 1.65$\times 10^{-6}$ M$_{\odot}$ yr$^{-1}$,
a value that is very close to the mass flux previously estimated for the SiO
jet and the H$_2$ outflow. These comparisons render HH211 the first embedded
system where an atomic jet is demonstrably shown to possess enough momentum to
drive the observed molecular jets and large scale outflows.
