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Sensitivity Of Pdr Calculations To Microphysical Details, N. P. Abel, P. A. M. Van Hoof, G. Shaw, Gary J. Ferland, T. Elwert
Sensitivity Of Pdr Calculations To Microphysical Details, N. P. Abel, P. A. M. Van Hoof, G. Shaw, Gary J. Ferland, T. Elwert
Physics and Astronomy Faculty Publications
Our understanding of physical processes in photodissociation regions or photon-dominated regions (PDRs) largely depends on the ability of spectral synthesis codes to reproduce the observed infrared emission-line spectrum. In this paper, we explore the sensitivity of a single PDR model to microphysical details. Our calculations use the Cloudy spectral synthesis code, recently modified to include a wealth of PDR physical processes. We show how the chemical/thermal structure of a PDR, along with the calculated spectrum, changes when the treatment of physical processes such as grain physics and atomic/molecular rates are varied. We find a significant variation in the intensities of …
On The Enhanced Cosmic-Ray Ionization Rate In The Diffuse Cloud Toward Ζ Persei, Gargi Shaw, Gary J. Ferland, R. Srianand, N. P. Abel, P. A. M. Van Hoof, P. C. Stancil
On The Enhanced Cosmic-Ray Ionization Rate In The Diffuse Cloud Toward Ζ Persei, Gargi Shaw, Gary J. Ferland, R. Srianand, N. P. Abel, P. A. M. Van Hoof, P. C. Stancil
Physics and Astronomy Faculty Publications
The spatial distribution of the cosmic-ray flux is important in understanding the interstellar medium (ISM) of the Galaxy. This distribution can be analyzed by studying different molecular species along different sight lines whose abundances are sensitive to the cosmic-ray ionization rate. Recently several groups have reported an enhanced cosmic-ray ionization rate (ζ=χCRζstandard) in diffuse clouds compared to the standard value, ζstandard (=2.5×10-17 s-1), measured toward dense molecular clouds. In an earlier work we reported an enhancement χCR=20 toward HD 185418. McCall et al. have reported χCR=48 toward ζ …