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Full-Text Articles in Physical Sciences and Mathematics
Continuum And Spectral Line Radiation From A Random Clumpy Medium, John E. Conway, Moshe Elitzur, Rodrigo Para
Continuum And Spectral Line Radiation From A Random Clumpy Medium, John E. Conway, Moshe Elitzur, Rodrigo Para
Physics and Astronomy Faculty Publications
We present a formalism for continuum and line emission from random clumpy media together with its application to problems of current interest, including CO spectral lines from ensembles of clouds and radio emission from H ii regions, supernovae, and star-forming regions. For line emission, we find that the effects of clump opacity on observed line ratios can be indistinguishable from variations of intrinsic line strengths, adding to the difficulties in determining abundances from line observations. Our formalism is applicable to arbitrary distributions of cloud properties, provided the cloud volume filling factor is small; numerical simulations show it to hold up …
Suppression Of Dielectronic Recombination Due To Finite Density Effects. Ii. Analytical Refinement And Application To Density-Dependent Ionization Balances And Agn Broad-Line Emission, D. Nikolić, T. W. Gorczyca, K. T. Korista, Marios Chatzikos, Gary J. Ferland, Francisco Guzmán, P. A. M. Van Hoof, R. J. R. Williams, N. R. Badnell
Suppression Of Dielectronic Recombination Due To Finite Density Effects. Ii. Analytical Refinement And Application To Density-Dependent Ionization Balances And Agn Broad-Line Emission, D. Nikolić, T. W. Gorczyca, K. T. Korista, Marios Chatzikos, Gary J. Ferland, Francisco Guzmán, P. A. M. Van Hoof, R. J. R. Williams, N. R. Badnell
Physics and Astronomy Faculty Publications
We present improved fits to our treatment of suppression of dielectronic recombination at intermediate densities. At low densities, most recombined excited states eventually decay to the ground state, and therefore the total dielectronic recombination rate to all levels is preserved. At intermediate densities, on the other hand, collisions can lead to ionization of higher-lying excited states, thereby suppressing the dielectronic recombination rate. The improved suppression factors presented here, although highly approximate, allow summed recombination rate coefficients to be used to intermediate densities. There have been several technical improvements to our previously presented fits. For H- through B-like ions the activation …
Molpop-Cep: An Exact, Fast Code For Multi-Level Systems, Andrés Asensio Ramos, Moshe Elitzur
Molpop-Cep: An Exact, Fast Code For Multi-Level Systems, Andrés Asensio Ramos, Moshe Elitzur
Physics and Astronomy Faculty Publications
We present MOLPOP-CEP, a universal line transfer code that allows the exact calculation of multi-level line emission from a slab with variable physical conditions for any arbitrary atom or molecule for which atomic data exist. The code includes error control to achieve any desired level of accuracy, providing full confidence in its results. Publicly available, MOLPOP-CEP employs our recently developed coupled escape probability (CEP) technique, whose performance exceeds other exact methods by orders of magnitude. The program also offers the option of an approximate solution with different variants of the familiar escape probability method. As an illustration of the MOLPOP-CEP …