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ISOCAM molecular hydrogen images of the CEP E outflow

Alberto Noriega-Crespo ¹, Peter M. Garnavich ², & Sergio Molinari ¹

¹ Infrared Processing and Analysis Center, California Institute of Technology and Jet Propulsion Laboratory, Pasadena, California 91125, USA

² Harvard-Smithsonian Center for Astrophysics

The physical characteristics of Cepheus E (Cep E) `embedded' outflow are analyzed using ISOCAM images in the v=0-0 S(5) 6.91 $\rm\mu m$ and S(3) 9.66 $\mu m$ molecular hydrogen lines. We find that the morphology of the Cep E outflow in the ground vibrational H2 lines is similar to that of the near infrared v=1-0 2.12 $\rm\mu m$ line. At these mid-IR wavelengths, we do not detect the second H2 outflow which is almost perpendicular to Cep E 2.121 $\rm\mu m$ flow or traces of H2 emission along the second 12CO J = 2-1 outflow at a 52 degrees angle, down to a surface brightness of 12 - 46 $\mu$ Jy/arcsec square.

We do detect at 6.91 $\rm\mu m$ the likely source of the main H₂ and CO outflows, IRAS 23011+6126, and show that the source is easily seen in all IRAS bands using HiRes images. The source is not detected at 9.66 $\rm\mu m$ , but we think this agrees with the interstellar extinction curve which has a minimum at 7 $\rm\mu m$ , but rises at 9.7 $\rm\mu m$ due to the strong absorption silicate feature, enhanced in this case by a cocoon surrounding the Class 0 object. This idea is supported by our models of the spectral energy distribution (SED) of the central object. The models assume that the main source of opacity is due to bare silicates and our best fit for the SED yields a total mass of envelope of 17 $\rm M_{\odot}$ and a dust temperature of 18 K.

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"The Universe as seen by ISO", 20 - 23 October 1998, Paris: Abstract Book