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Session 42 - Molecular Clouds: Models and Observations.
Display session, Tuesday, June 11
Great Hall,

[42.09] NGC 7023: Radiative Transfer in a Clumpy Nebula from the far-UV to the IR

K. D. Gordon, A. N. Witt (U. Toledo), R. C. Bohlin (STSCI), R. W. O'Connell (UVA), M. S. Roberts (NRAO), S. G. Neff, A. T. Smith, T. P. Stecher (NASA/GSFC)

During the ASTRO2 mission, the Ultraviolet Imaging Telescope (UIT) obtained new far-UV images of the bright reflection nebula NGC 7023. Combining these observations with previous ASTRO1/UIT, optical, and IR observations results in a picture of the nebula which cannot be explained by radiative transfer models with homogeneous dust distributions. Specifically, homogeneous models underpredict the IR surface brightness by factors of 2--4 (Sellgren et al.\ 1992, ApJ, 400, 238). In addition, the IR images show a very clumpy structure. Thus, we use a radiative transfer model with a clumpy dust distribution to compute the surface brightness of NGC 7023 from the far-UV to the IR. We will present a model which reproduces the surface brightness levels from the far-UV to the IR and also produces similar structure to that observed in the IR. This model allows us to determine values for the dust albedo and scattering phase function asymmetry (g) from the far-UV to the IR. This work was supported by NASA through LTSA Grant NAGW-3168 to The University of Toledo.

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