The Ionization of Planetary Nebulae : Proceedings of the 34th IAU Symposium
| dc.contributor.author | Williams, R. E. | |
| dc.date.accessioned | 2017-06-02T19:59:08Z | |
| dc.date.available | 2017-06-02T19:59:08Z | |
| dc.date.issued | 1967-08 | |
| dc.identifier.citation | Planetary Nebulae / D. E. Osterbrock and C. R. O'Dell (eds.): 190-204 (1968) | en |
| dc.identifier.uri | http://hdl.handle.net/10150/623821 | |
| dc.description.abstract | The ionization of the most abundant elements in planetary nebulae has been determined for a number of models of nebulae at different epochs in their expansion. The values used for the temperatures and radii of the central stars and the sizes and densities of the shells have come from Seaton's evolutionary sequence. The ionizing radiation field has been taken from model atmosphere calculations of the central stars by Gebbie and Seaton, and Biihm and Deinzer. Emission -line fluxes have been calculated for the models and compared with observations of planetary nebulae by O'Dell, Osterbrock's group, and Aller and his collaborators. Results indicate that the central stars have strong He+ Lyman continuum excesses, similar to those predicted by Gebbie and Seaton. The mean abundance determinations for the nebulae made by Aller are confirmed, with the exception of nitrogen, which appears to be 3 or 4 times more abundant than his value. It is also seen that the electron temperatures of the nebulae are higher than previous theoretical determinations, providing better agreement with empirically derived values. | |
| dc.language.iso | en_US | en |
| dc.publisher | Steward Observatory, The University of Arizona (Tucson, Arizona) | en |
| dc.relation.ispartofseries | Preprints of the Steward Observatory #10 | en |
| dc.relation.url | http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1968IAUS...34..190W&db_key=AST&data_type=HTML&format=&high=3ed65e9cd024029 | en |
| dc.rights | Copyright © All Rights Reserved. | en |
| dc.source | Steward Observatory Parker Library SO QB 4 .S752 ARCH | en |
| dc.subject | Planetary nebulae | en |
| dc.subject | Ionization | en |
| dc.title | The Ionization of Planetary Nebulae : Proceedings of the 34th IAU Symposium | en_US |
| dc.type | text | en |
| dc.type | Article | en |
| dc.contributor.department | Univ Arizona, Steward Observ | en |
| dc.description.collectioninformation | This title from the Steward Observatory Preprints collection is made available by the Steward Observatory Parker Library and the University Libraries, The University of Arizona. If you have questions about titles in this collection, please contact Parker Library librarian Betty Fridena, bfridena@as.arizona.edu. | en |
| refterms.dateFOA | 2018-09-11T19:47:17Z | |
| html.description.abstract | The ionization of the most abundant elements in planetary nebulae has been determined for a number of models of nebulae at different epochs in their expansion. The values used for the temperatures and radii of the central stars and the sizes and densities of the shells have come from Seaton's evolutionary sequence. The ionizing radiation field has been taken from model atmosphere calculations of the central stars by Gebbie and Seaton, and Biihm and Deinzer. Emission -line fluxes have been calculated for the models and compared with observations of planetary nebulae by O'Dell, Osterbrock's group, and Aller and his collaborators. Results indicate that the central stars have strong He+ Lyman continuum excesses, similar to those predicted by Gebbie and Seaton. The mean abundance determinations for the nebulae made by Aller are confirmed, with the exception of nitrogen, which appears to be 3 or 4 times more abundant than his value. It is also seen that the electron temperatures of the nebulae are higher than previous theoretical determinations, providing better agreement with empirically derived values. |
