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R.B. Anderson (University of Michigan), S.T. Megeath, P.C. Myers (Harvard/Smithsonian Center for Astrophysics)
The structure of molecular clouds is not well understood due to the difficulties in mapping the column density with high angular resolution. We propose a new method for mapping structure in regions with extended diffuse emission due to stochastic heating of Polycyclic Aromatic Hydrocarbons (PAHs). This new method uses the absorption in the 5.8\mum and 8.0\mum band of the InfraRed Array Camera (IRAC) on the \emph{Spitzer} space telescope. We model how both the observed surface brightness, and the ratio of the surface brightnesses in these bands, depend on the amount of foreground extinction. By comparing the results of these models with the observed absorption in these bands, we attempt to measure the extinction across well-defined filaments in the OMC2/3 region of the Orion A molecular cloud. We compare these results with the expected extinction for an isothermal cylinder. Finally, we discuss the uncertainties in this method, and the discrepancies between predicted and observed ratios of surface brightness in the 5.8\micron~ and 8.0\micron~ bands. This research was made possible by the Research Experiences for Undergraduates program funded by the NSF, grant no. 9731923.
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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.