Optical recombination lines and temperature fluctuations
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| Format: | Artículo científico |
| Language: | en |
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Universidad Nacional Autónoma de México
2002
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| _version_ | 1876442695373684736 |
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| author | X. W. Liu |
| author_facet | X. W. Liu |
| contents | Optical recombination lines and temperature fluctuations X. W. Liu Física, Astronomía y Matemáticas ISM: ABUNDANCES ATOMIC PROCESSES PLANETARY NEBULAE Three decades ago, Peimbert found that in H II regions and planetary nebulae (PNe) Balmer jump temperaturesare systematically lower than [O III] forbidden line temperatures. He suggested that because there are largetemperature uctuations in nebulae, as a consequence, heavy element abundances derived from collisionallyexcited lines (CELs) have been systematically underestimated. In this article, I review the recent abundancedeterminations for PNe using faint heavy element optical recombination lines (ORLs). For all the ionic speciesstudied, ORLs yield higher abundances than CELs. The ratio of ORL to CEL abundances varies from objectto object and correlates with the di erence between the [O III] and Balmer jump temperatures. Temperatureand/or density uctuations alone are found to be insucient to explain the very large discrepancies betweenthe ORL and CEL abundances observed in a small number of nebulae. It is suggested that these extremenebulae may contain metal-rich inclusions similar to those observed in \born-again" PN such as Abell 30. 2002 artículo científico 0185-1101 https://www.redalyc.org/articulo.oa?id=57112026 en http://www.redalyc.org/revista.oa?id=571 Revista Mexicana de Astronomía y Astrofísica application/pdf Universidad Nacional Autónoma de México Revista Mexicana de Astronomía y Astrofísica (México) Vol.12 |
| format | Artículo científico |
| id | redalyc_57112026 |
| institution | Redalyc |
| language | en |
| publishDate | 2002 |
| publisher | Universidad Nacional Autónoma de México |
| spellingShingle | Optical recombination lines and temperature fluctuations X. W. Liu Física, Astronomía y Matemáticas ISM: ABUNDANCES ATOMIC PROCESSES PLANETARY NEBULAE Optical recombination lines and temperature fluctuations X. W. Liu Física, Astronomía y Matemáticas ISM: ABUNDANCES ATOMIC PROCESSES PLANETARY NEBULAE Three decades ago, Peimbert found that in H II regions and planetary nebulae (PNe) Balmer jump temperaturesare systematically lower than [O III] forbidden line temperatures. He suggested that because there are largetemperature uctuations in nebulae, as a consequence, heavy element abundances derived from collisionallyexcited lines (CELs) have been systematically underestimated. In this article, I review the recent abundancedeterminations for PNe using faint heavy element optical recombination lines (ORLs). For all the ionic speciesstudied, ORLs yield higher abundances than CELs. The ratio of ORL to CEL abundances varies from objectto object and correlates with the di erence between the [O III] and Balmer jump temperatures. Temperatureand/or density uctuations alone are found to be insucient to explain the very large discrepancies betweenthe ORL and CEL abundances observed in a small number of nebulae. It is suggested that these extremenebulae may contain metal-rich inclusions similar to those observed in \born-again" PN such as Abell 30. 2002 artículo científico 0185-1101 https://www.redalyc.org/articulo.oa?id=57112026 en http://www.redalyc.org/revista.oa?id=571 Revista Mexicana de Astronomía y Astrofísica application/pdf Universidad Nacional Autónoma de México Revista Mexicana de Astronomía y Astrofísica (México) Vol.12 |
| title | Optical recombination lines and temperature fluctuations |
| topic | Física, Astronomía y Matemáticas ISM: ABUNDANCES ATOMIC PROCESSES PLANETARY NEBULAE |
| url | https://www.redalyc.org/articulo.oa?id=57112026 |