The interstellar medium located in between the stars is heterogeneous and have regions of relatively high densities called interstellar clouds. These clouds are found to be rich of chemistry.  When exposed to high flux Far-Ultraviolet (FUV) radiation from nearby stars, interstellar clouds are transformed into Photon Dominated Regions (PDRs).    When photons with energies of 6-13.6 eV penetrate PDRs, they cause photo-ionization and photo-dissociation of chemical species in these regions. As the radiation passes through the interstellar cloud, the photons are absorbed, scattered or diffracted.  For this reason, the photon flux is large on the outer rims of the PDRs and the radiation disperses as it travels through the region, hence the extreme contrast in temperature from the outer to inner depths of the PDR respectively.  Therefore, the distribution of chemical species varies significantly in different parts of PDRs.  To study the complex physical conditions and their sequences in PDRs, physical models are needed.  The modeling will be carried out by dividing the PDRs into thin layers and studying the physical conditions from layer to layer. Within each layer the physical conditions will be kept homogeneous, but for different layers, the physical conditions will change according to the depth the light must travel.  Comparison of modeled abundances of the species in PDRs with observational results will be presented.

Modeling physical conditions of photon dominated regions in the interstellar medium

246th National Meeting (2013)

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