2008/08/19 by N. P. Abel, P. A. M. van Hoof, G. Shaw +3
Chemistry · Earth and Planetary Sciences · Physics and Astronomy · #Astrophysics #Astrophysics and Star Formation Studies #Atmospheric Ozone and Climate #Atmospheric chemistry and aerosols #Atomic physics #Chemistry #Computational physics #Cosmic ray #Grain size #Infrared #Ion #Ionization #Materials science #Optics #Photodissociation #Photon #Physics #Sensitivity (control systems) #Spectral line #astro-ph
paper · pdf · doi:10.1086/591505
36 pages, 17 figures, accepted for publication in ApJ
arxiv created 2008/08/19 · openalex publication_date 2008/10/17 · arxiv updated 2009/12/01 · openalex created_date 2020/11/23 · openalex updated_date 2026/08/05
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 PDR emission lines, depending on different treatments of the grain physics. We also show how different combinations of the cosmic-ray ionization rate, inclusion of grain-atom/ion charge transfer, and the grain size distribution can lead to very similar results for the chemical structure. In addition, our results show the utility of Cloudy for the spectral modeling of molecular environments.