Discovery of a primordial water reservoir in the envelope of HH211
  We report on the detection of a rich water reservoir in the protostellar
envelope of the Class 0 source HH211. In striking contrast to all other
molecules detected with Herschel/PACS, water emission peaks around the central
source where both ortho and para forms are detected. The measured ortho-to-para
ratio of just 0.65 indicates formation of water-ice at very low temperatures
and a non-destructive photo-desorption process around the protostar. While part
of the water emission is likely related to collisional excitation, the
centralized morphology around the protostar suggests that radiative excitation
is also significant, despite the fact that radiation appears to have a very
different impact on the water molecules when compared to the terminal outflow
shocks. The very low ortho-to-para ratio suggests that water around the
protostar originates from primordial envelope material that has never been
thermally processed before.
