Molecular chemistry and the missing mass problem in planetary nebulae
Autor(a) principal: | |
---|---|
Data de Publicação: | 2012 |
Outros Autores: | , |
Tipo de documento: | Artigo |
Idioma: | eng |
Título da fonte: | Repositório Institucional da UFRGS |
Texto Completo: | http://hdl.handle.net/10183/99092 |
Resumo: | Context. Detections of molecular lines, mainly from H₂ and CO, reveal molecular material in planetary nebulae. Observations of a variety of molecules suggest that the molecular composition in these objects differs from that found in interstellar clouds or in circumstellar envelopes. The success of the models, which are mostly devoted to explain molecular densities in specific planetary nebulae, is still partial however. Aims. The present study aims at identifying the influence of stellar and nebular properties on the molecular composition of planetary nebulae by means of chemical models. A comparison of theoretical results with those derived from the observations may provide clues to the conditions that favor the presence of a particular molecule. Methods. A self-consistent photoionization numerical code was adapted to simulate cold molecular regions beyond the ionized zone. The code was used to obtain a grid of models and the resulting column densities are compared with those inferred from observations. Results. Our models show that the inclusion of an incident flux of X-rays is required to explain the molecular composition derived for planetary nebulae. We also obtain a more accurate relation for the N(CO)/N(H₂) ratio in these objects. Molecular masses obtained by previous works in the literature were then recalculated, showing that these masses can be underestimated by up to three orders of magnitude. We conclude that the problem of the missing mass in planetary nebulae can be solved by a more accurate calculation of the molecular mass. |
id |
UFRGS-2_0f3674d90faf4ce6e82599f0e878b516 |
---|---|
oai_identifier_str |
oai:www.lume.ufrgs.br:10183/99092 |
network_acronym_str |
UFRGS-2 |
network_name_str |
Repositório Institucional da UFRGS |
repository_id_str |
|
spelling |
Kimura, Rafael KobataGruenwald, Ruth B.Aleman, Isabel Regina Guerra2014-08-05T02:07:37Z20120004-6361http://hdl.handle.net/10183/99092000900161Context. Detections of molecular lines, mainly from H₂ and CO, reveal molecular material in planetary nebulae. Observations of a variety of molecules suggest that the molecular composition in these objects differs from that found in interstellar clouds or in circumstellar envelopes. The success of the models, which are mostly devoted to explain molecular densities in specific planetary nebulae, is still partial however. Aims. The present study aims at identifying the influence of stellar and nebular properties on the molecular composition of planetary nebulae by means of chemical models. A comparison of theoretical results with those derived from the observations may provide clues to the conditions that favor the presence of a particular molecule. Methods. A self-consistent photoionization numerical code was adapted to simulate cold molecular regions beyond the ionized zone. The code was used to obtain a grid of models and the resulting column densities are compared with those inferred from observations. Results. Our models show that the inclusion of an incident flux of X-rays is required to explain the molecular composition derived for planetary nebulae. We also obtain a more accurate relation for the N(CO)/N(H₂) ratio in these objects. Molecular masses obtained by previous works in the literature were then recalculated, showing that these masses can be underestimated by up to three orders of magnitude. We conclude that the problem of the missing mass in planetary nebulae can be solved by a more accurate calculation of the molecular mass.application/pdfengAstronomy and astrophysics. Les Ulis. Vol. 541 (May 2012), A112, 11 p.Matéria circumestelarAstroquímicaMoleculas interestelaresMatéria circumestelarNuvens moleculares interestelaresNebulosas planetariasFotoionizacaoAstrochemistryISM: moleculessPlanetary nebulae: generalMolecular chemistry and the missing mass problem in planetary nebulaeEstrangeiroinfo:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/openAccessreponame:Repositório Institucional da UFRGSinstname:Universidade Federal do Rio Grande do Sul (UFRGS)instacron:UFRGSORIGINAL000900161.pdf000900161.pdfTexto completo (inglês)application/pdf882476http://www.lume.ufrgs.br/bitstream/10183/99092/1/000900161.pdfbbff16dafbb3ff3b9f701e6b59accdf6MD51TEXT000900161.pdf.txt000900161.pdf.txtExtracted Texttext/plain56585http://www.lume.ufrgs.br/bitstream/10183/99092/2/000900161.pdf.txte3b910a60345df211264830fb168cb06MD52THUMBNAIL000900161.pdf.jpg000900161.pdf.jpgGenerated Thumbnailimage/jpeg1993http://www.lume.ufrgs.br/bitstream/10183/99092/3/000900161.pdf.jpgb84e81cfa683c7965d5358af87905f43MD5310183/990922018-10-22 08:26:43.238oai:www.lume.ufrgs.br:10183/99092Repositório de PublicaçõesPUBhttps://lume.ufrgs.br/oai/requestopendoar:2018-10-22T11:26:43Repositório Institucional da UFRGS - Universidade Federal do Rio Grande do Sul (UFRGS)false |
dc.title.pt_BR.fl_str_mv |
Molecular chemistry and the missing mass problem in planetary nebulae |
title |
Molecular chemistry and the missing mass problem in planetary nebulae |
spellingShingle |
Molecular chemistry and the missing mass problem in planetary nebulae Kimura, Rafael Kobata Matéria circumestelar Astroquímica Moleculas interestelares Matéria circumestelar Nuvens moleculares interestelares Nebulosas planetarias Fotoionizacao Astrochemistry ISM: moleculess Planetary nebulae: general |
title_short |
Molecular chemistry and the missing mass problem in planetary nebulae |
title_full |
Molecular chemistry and the missing mass problem in planetary nebulae |
title_fullStr |
Molecular chemistry and the missing mass problem in planetary nebulae |
title_full_unstemmed |
Molecular chemistry and the missing mass problem in planetary nebulae |
title_sort |
Molecular chemistry and the missing mass problem in planetary nebulae |
author |
Kimura, Rafael Kobata |
author_facet |
Kimura, Rafael Kobata Gruenwald, Ruth B. Aleman, Isabel Regina Guerra |
author_role |
author |
author2 |
Gruenwald, Ruth B. Aleman, Isabel Regina Guerra |
author2_role |
author author |
dc.contributor.author.fl_str_mv |
Kimura, Rafael Kobata Gruenwald, Ruth B. Aleman, Isabel Regina Guerra |
dc.subject.por.fl_str_mv |
Matéria circumestelar Astroquímica Moleculas interestelares Matéria circumestelar Nuvens moleculares interestelares Nebulosas planetarias Fotoionizacao |
topic |
Matéria circumestelar Astroquímica Moleculas interestelares Matéria circumestelar Nuvens moleculares interestelares Nebulosas planetarias Fotoionizacao Astrochemistry ISM: moleculess Planetary nebulae: general |
dc.subject.eng.fl_str_mv |
Astrochemistry ISM: moleculess Planetary nebulae: general |
description |
Context. Detections of molecular lines, mainly from H₂ and CO, reveal molecular material in planetary nebulae. Observations of a variety of molecules suggest that the molecular composition in these objects differs from that found in interstellar clouds or in circumstellar envelopes. The success of the models, which are mostly devoted to explain molecular densities in specific planetary nebulae, is still partial however. Aims. The present study aims at identifying the influence of stellar and nebular properties on the molecular composition of planetary nebulae by means of chemical models. A comparison of theoretical results with those derived from the observations may provide clues to the conditions that favor the presence of a particular molecule. Methods. A self-consistent photoionization numerical code was adapted to simulate cold molecular regions beyond the ionized zone. The code was used to obtain a grid of models and the resulting column densities are compared with those inferred from observations. Results. Our models show that the inclusion of an incident flux of X-rays is required to explain the molecular composition derived for planetary nebulae. We also obtain a more accurate relation for the N(CO)/N(H₂) ratio in these objects. Molecular masses obtained by previous works in the literature were then recalculated, showing that these masses can be underestimated by up to three orders of magnitude. We conclude that the problem of the missing mass in planetary nebulae can be solved by a more accurate calculation of the molecular mass. |
publishDate |
2012 |
dc.date.issued.fl_str_mv |
2012 |
dc.date.accessioned.fl_str_mv |
2014-08-05T02:07:37Z |
dc.type.driver.fl_str_mv |
Estrangeiro info:eu-repo/semantics/article |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
format |
article |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
http://hdl.handle.net/10183/99092 |
dc.identifier.issn.pt_BR.fl_str_mv |
0004-6361 |
dc.identifier.nrb.pt_BR.fl_str_mv |
000900161 |
identifier_str_mv |
0004-6361 000900161 |
url |
http://hdl.handle.net/10183/99092 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.relation.ispartof.pt_BR.fl_str_mv |
Astronomy and astrophysics. Les Ulis. Vol. 541 (May 2012), A112, 11 p. |
dc.rights.driver.fl_str_mv |
info:eu-repo/semantics/openAccess |
eu_rights_str_mv |
openAccess |
dc.format.none.fl_str_mv |
application/pdf |
dc.source.none.fl_str_mv |
reponame:Repositório Institucional da UFRGS instname:Universidade Federal do Rio Grande do Sul (UFRGS) instacron:UFRGS |
instname_str |
Universidade Federal do Rio Grande do Sul (UFRGS) |
instacron_str |
UFRGS |
institution |
UFRGS |
reponame_str |
Repositório Institucional da UFRGS |
collection |
Repositório Institucional da UFRGS |
bitstream.url.fl_str_mv |
http://www.lume.ufrgs.br/bitstream/10183/99092/1/000900161.pdf http://www.lume.ufrgs.br/bitstream/10183/99092/2/000900161.pdf.txt http://www.lume.ufrgs.br/bitstream/10183/99092/3/000900161.pdf.jpg |
bitstream.checksum.fl_str_mv |
bbff16dafbb3ff3b9f701e6b59accdf6 e3b910a60345df211264830fb168cb06 b84e81cfa683c7965d5358af87905f43 |
bitstream.checksumAlgorithm.fl_str_mv |
MD5 MD5 MD5 |
repository.name.fl_str_mv |
Repositório Institucional da UFRGS - Universidade Federal do Rio Grande do Sul (UFRGS) |
repository.mail.fl_str_mv |
|
_version_ |
1801224843417354240 |