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Chemical modeling of L183 (L134N): an estimate of the ortho/para H{_2} ratio

hal.structure.identifierLaboratoire d'Etude du Rayonnement et de la Matière en Astrophysique [LERMA]
dc.contributor.authorPAGANI, L.
hal.structure.identifierCentre d'étude spatiale des rayonnements [CESR]
hal.structure.identifierCentre d'étude spatiale des rayonnements [CESR]
dc.contributor.authorVASTEL, C.
hal.structure.identifierTechnologies et systèmes d'information pour les agrosystèmes [UR TSCF]
dc.contributor.authorHUGO, E.
hal.structure.identifierLaboratoire Aimé Cotton [LAC]
hal.structure.identifierDepartment of Physics [Orlando] [UCF | Physics]
dc.contributor.authorKOKOOULINE, V.
dc.contributor.authorGREENE, C. H.
hal.structure.identifierLaboratoire d'Astrophysique de Grenoble [LAOG]
hal.structure.identifierLaboratoire d'Astrophysique de Bordeaux [Pessac] [LAB]
hal.structure.identifierObservatoire aquitain des sciences de l'univers [OASU]
hal.structure.identifierUniversité Sciences et Technologies - Bordeaux 1 [UB]
dc.contributor.authorBACMANN, A.
hal.structure.identifierLaboratoire de Radioastronomie [LRA]
dc.contributor.authorBAYET, Estelle
hal.structure.identifierLaboratoire d'Astrophysique de Grenoble [LAOG]
dc.contributor.authorCECCARELLI, C.
dc.contributor.authorPENG, R.
hal.structure.identifierI. Physikalisches Institut [Köln]
dc.contributor.authorSCHLEMMER, S.
dc.date.issued2009-02
dc.identifier.issn0004-6361
dc.description.abstractEnContext: The high degree of deuteration observed in some prestellar cores depends on the ortho-to-para H2 ratio through the H3+ fractionation. Aims: We want to constrain the ortho/para H2 ratio across the L183 prestellar core. This is required to correctly describe the deuteration amplification phenomenon in depleted cores such as L183 and to relate the total (ortho+para) H2D+ abundance to the sole ortho-H2D+ column density measurement. Methods: To constrain this ortho/para H2 ratio and derive its profile, we make use of the N2D^+/N2H+ ratio and of the ortho-H2D+ observations performed across the prestellar core. We use two simple chemical models limited to an almost totally depleted core description. New dissociative recombination and trihydrogen cation-dihydrogen reaction rates (including all isotopologues) are presented in this paper and included in our models. Results: We estimate the H2D+ ortho/para ratio in the L183 cloud, and constrain the H2 ortho/para ratio: we show that it varies across the prestellar core by at least an order of magnitude, being still very high (≈0.1) in most of the cloud. Our time-dependent model indicates that the prestellar core is presumably older than 1.5-2 × 105 years but that it may not be much older. We also show that it has reached its present density only recently and that its contraction from a uniform density cloud can be constrained. Conclusions: A proper understanding of deuteration chemistry cannot be attained without taking into account the whole ortho/para family of molecular hydrogen and trihydrogen cation isotopologues as their relations are of utmost importance in the global scheme. Tracing the ortho/para H2 ratio should also place useful constraints on the dynamical evolution of prestellar cores. Appendices A and B are only available in electronic form at http://www.aanda.org
dc.language.isoen
dc.publisherEDP Sciences
dc.subject.enISM: abundances
dc.subject.enISM: clouds
dc.subject.enISM: structure
dc.subject.enastrochemistry
dc.subject.enISM: individual objects: L183
dc.subject.enmolecular processes
dc.title.enChemical modeling of L183 (L134N): an estimate of the ortho/para H{_2} ratio
dc.typeArticle de revue
dc.identifier.doi10.1051/0004-6361:200810587
dc.subject.halPlanète et Univers [physics]/Astrophysique [astro-ph]/Astrophysique galactique [astro-ph.GA]
dc.subject.halPhysique [physics]/Astrophysique [astro-ph]/Astrophysique galactique [astro-ph.GA]
dc.identifier.arxiv0810.1861
bordeaux.journalAstronomy and Astrophysics - A&A
bordeaux.page623-636
bordeaux.volume494
bordeaux.peerReviewedoui
hal.identifierhal-00633468
hal.version1
hal.popularnon
hal.audienceInternationale
hal.origin.linkhttps://hal.archives-ouvertes.fr//hal-00633468v1
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