Herschel-PACS spectroscopy of the intermediate mass protostar NGC7129
  FIRS 2
  Aims: We present preliminary results of the first Herschel spectroscopic
observations of NGC7129 FIRS2, an intermediate mass star-forming region. We
attempt to interpret the observations in the framework of an in-falling
spherical envelope. Methods: The PACS instrument was used in line spectroscopy
mode (R=1000-5000) with 15 spectral bands between 63 and 185 microns. This
provided good detections of 26 spectral lines seen in emission, including lines
of H2O, CO, OH, O I, and C II. Results: Most of the detected lines,
particularly those of H2O and CO, are substantially stronger than predicted by
the spherical envelope models, typically by several orders of magnitude. In
this paper we focus on what can be learned from the detected CO emission lines.
Conclusions: It is unlikely that the much stronger than expected line emission
arises in the (spherical) envelope of the YSO. The region hot enough to produce
such high excitation lines within such an envelope is too small to produce the
amount of emission observed. Virtually all of this high excitation emission
must arise in structures such as as along the walls of the outflow cavity with
the emission produced by a combination of UV photon heating and/or
non-dissociative shocks.
