The photon dominated region in the IC 348 molecular cloud. Sun, K., Ossenkopf, V., Kramer, C., Mookerjea, B., Röllig, M., Cubick, M., & Stutzki, J. Astronomy and Astrophysics, 489(1):207-216, 10, 2008.
The photon dominated region in the IC 348 molecular cloud [pdf]Pdf 0  The photon dominated region in the IC 348 molecular cloud [link]Mendeley  The photon dominated region in the IC 348 molecular cloud [link]Paper  doi  abstract   bibtex   
In this paper we discuss the physical conditions of clumpy nature in the IC 348 molecular cloud. We combine new observations of fully sampled maps in C I at 492 GHz and 12CO 4-3, taken with the KOSMA 3 m telescope at about 1' resolution, with FCRAO data of 12CO 1-0, 13CO 1-0 and far-infrared continuum data observed by HIRES/IRAS. To derive the physical parameters of the region we analyze the three different line ratios. A first rough estimate of abundance is obtained from an LTE analysis. To understand the C I and CO emission from the PDRs in IC 348, we use a clumpy PDR model. With an ensemble of identical clumps, we constrain the total mass from the observed absolute intensities. Then we apply a more realistic clump distribution model with a power law index of 1.8 for clump-mass spectrum and a power law index of 2.3 for mass-size relation. We provide detailed fits to observations at seven representative positions in the cloud, revealing clump densities between 4 10^4 cm^-3 and 4 10^5 cm^-3 and C/CO column density ratios between 0.02 and 0.26. The derived FUV flux from the model fit is consistent with the field calculated from FIR continuum data, varying between 2 and 100 Draine units across the cloud. We find that both an ensemble of identical clumps and an ensemble with a power law clump mass distribution produce line intensities which are in good agreement (within a factor ~ 2) with the observed intensities. The models confirm the anti-correlation between the C/CO abundance ratio and the hydrogen column density found in many regions.

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