RECOMBINATION AND COLLISIONALLY EXCITED BALMER LINES
We present a model for the statistical equilibrium of the lev els of H, consi- dering recombinations to excited levels, collisional exci tations up from the ground state and spontaneous radiative transitions. This problem has a simple “cascade matrix” solution, describing a cascade of downwards spon...
| Authors: | , , , , |
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| Format: | article |
| Status: | Published version |
| Publication Date: | 2015 |
| Country: | México |
| Institution: | Universidad Nacional Autónoma de México |
| Repository: | Redalyc-UNAM |
| OAI Identifier: | oai:redalyc.org:57143120009 |
| Online Access: | https://www.redalyc.org/articulo.oa?id=57143120009 https://www.redalyc.org/journal/571/57143120009/ https://www.redalyc.org/journal/571/57143120009/html/ https://www.redalyc.org/journal/571/57143120009/57143120009.epub https://www.redalyc.org/journal/571/57143120009/movil |
| Access Level: | Open access |
| Keyword: | Física, Astronomía y Matemáticas HH2) Herbig shock waves Haro objects hydrodynamics |
| Summary: | We present a model for the statistical equilibrium of the lev els of H, consi- dering recombinations to excited levels, collisional exci tations up from the ground state and spontaneous radiative transitions. This problem has a simple “cascade matrix” solution, describing a cascade of downwards sponta neous transitions fed by both recombinations and collisional excitations. The re sulting predicted Balmer line ratios show a transition between a low temperature and a high temperature regime (dominated by recombinations and by collisional exc itations, respectively), both with only a weak line ratio vs. temperature dependence. This clear character- istic allows a direct observational identification of regio ns in which the Balmer lines are either recombination or collisionally excited transit ions. We find that for a gas in coronal ionization equilibrium the H α and H β lines are collisionally excited for all temperatures. In order to have recombination H α and H β it is necessary to have higher ionization fractions of H than the ones obtained from coronal equilibrium (e.g., such as the ones found in a photoionized gas). |
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