September 2004 • 2004ApJS..154..402N
Abstract • New early release observations of the Cepheus E outflow and its embedded source, obtained with the Spitzer Space Telescope, are presented. We show that the driving source is detected in all four Infrared Array Camera (IRAC) bands, which suggests that traditional Class 0 classification, although essentially correct, needs to accommodate the new high-sensitivity infrared arrays and their ability to detect deeply embedded sources. Thus, we have determined a slope of the mid-infrared spectral energy distribution to be a=5+/-1 using only the IRAC fluxes. The IRAC and Multiband Imaging Photometer for Spitzer (MIPS) 24 and 70 μm new photometric points are consistent with a spectral energy distribution dominated by a cold, dense envelope surrounding the protostar. The Cep E outflow displays a very similar morphology in the near- and mid-infrared wavelengths and is detected at 24 μm. The interface between the dense molecular gas (where Cep E lies) and the less dense interstellar medium is well traced by the emission at 8 and 24 μm and is one of the most exotic features of the new IRAC and MIPS images. IRS observations of the north lobe of the flow confirm that most of the emission is due to the excitation of pure H2 rotational transitions arising from a relatively cold (Tex~700 K) and dense (6.4×104 cm-3) molecular gas.