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Molecular cloud chemistry and the importance of dielectronic recombination

hal.structure.identifierColumbia Astrophysics Laboratory [CAL]
dc.contributor.authorBRYANS, P.
hal.structure.identifierColumbia Astrophysics Laboratory [CAL]
dc.contributor.authorKRECKEL, H.
hal.structure.identifierLaboratoire Univers et Théories [LUTH (UMR_8102)]
dc.contributor.authorROUEFF, E.
hal.structure.identifierObservatoire aquitain des sciences de l'univers [OASU]
hal.structure.identifierLaboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux [L3AB]
hal.structure.identifierLaboratoire d'Astrophysique de Bordeaux [Pessac] [LAB]
dc.contributor.authorWAKELAM, Valentine
hal.structure.identifierFachbereich Physik [Duisburg]
dc.contributor.authorSAVIN, D. W.
dc.date.issued2009
dc.identifier.issn0004-637X
dc.description.abstractEnDielectronic recombination (DR) of singly charged ions is a reaction pathway that is commonly neglected in chemical models of molecular clouds. In this study we include state-of-the-art DR data for He$^+$, C$^+$, N$^+$, O$^+$, Na$^+$, and Mg$^+$ in chemical models used to simulate dense molecular clouds, protostars, and diffuse molecular clouds. We also update the radiative recombination (RR) rate coefficients for H$^+$, He$^+$, C$^+$, N$^+$, O$^+$, Na$^+$, and Mg$^+$ to the current state-of-the-art values. The new RR data has little effect on the models. However, the inclusion of DR results in significant differences in gas-grain models of dense, cold molecular clouds for the evolution of a number of surface and gas-phase species. We find differences of a factor of 2 in the abundance for 74 of the 655 species at times of $10^4$--$10^6$ years in this model when we include DR. Of these 74 species, 16 have at least a factor of 10 difference in abundance. We find the largest differences for species formed on the surface of dust grains. These differences are due primarily to the addition of C$^+$ DR, which increases the neutral C abundance, thereby enhancing the accretion of C onto dust. These results may be important for the warm-up phase of molecular clouds when surface species are desorbed into the gas phase. We also note that no reliable state-of-the-art RR or DR data exist for Si$^+$, P$^+$, S$^+$, Cl$^+$, and Fe$^+$. Modern calculations for these ions are needed to better constrain molecular cloud models.
dc.language.isoen
dc.publisherAmerican Astronomical Society
dc.subject.enastrochemistry — atomic data — atomic processes — ISM: atoms — dust
dc.subject.enextinction — ISM: molecules
dc.title.enMolecular cloud chemistry and the importance of dielectronic recombination
dc.typeArticle de revue
dc.identifier.doi10.1088/0004-637X/694/1/286
dc.subject.halPhysique [physics]/Astrophysique [astro-ph]/Cosmologie et astrophysique extra-galactique [astro-ph.CO]
dc.subject.halPlanète et Univers [physics]/Astrophysique [astro-ph]/Planétologie et astrophysique de la terre [astro-ph.EP]
dc.subject.halPhysique [physics]/Astrophysique [astro-ph]/Planétologie et astrophysique de la terre [astro-ph.EP]
dc.identifier.arxiv0809.4504
bordeaux.journalThe Astrophysical Journal
bordeaux.page286-293
bordeaux.volume694
bordeaux.issue1
bordeaux.peerReviewedoui
hal.identifierhal-00398339
hal.version1
hal.popularnon
hal.audienceInternationale
hal.origin.linkhttps://hal.archives-ouvertes.fr//hal-00398339v1
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