Summary: Multi-wavelength spectroscopy of the bipolar out ow from
Cepheus E 1
Michael D. Smith
Armagh Observatory, College Hill, Armagh BT61 9DG, Northern Ireland
Dirk Froebrich, Jochen Eisloel
Thuringer Landessternwarte Tautenburg, Sternwarte 5, D-07778 Tautenburg, Germany
ABSTRACT
Cepheus E is the site of an exceptional example of a protostellar out ow with a very young
dynamical age and extremely high near infrared luminosity. We combine molecular spectroscopic
data from the submillimeter to the near infrared in order to interpret the rotational excita-
tion of CO and the ro-vibrational excitation of H 2 . We conclude that C-type shocks with a
paraboloidal bow shock geometry can simultaneously explain all the molecular excitations. A
dierence in the extinction between the red and blue-shifted out ow lobe accounts
for the measured ux dierence and the deviation of the column densities from local
thermodynamic equilibrium. The out ow is deeply embedded in a quite dense clump
(density greater than 10 5 cm 3 ), yet a good fraction of atomic hydrogen, about 40%, is
required to explain the excitation and statistical equilibrium. We propose that this atomic com-
ponent arises, self-consistently, from the dissociated gas at the apex of the leading bow shocks and
the relatively long molecule reformation time. At least 20 bow shocks are required in each lobe,
although these may be sub-divided into smaller bows and turbulent shocked regions. The total

Source: Armagh Observatory

Collections: Physics