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Chemistry in disks I - Deep search for N$_2$H$^+$ in the protoplanetary disks around LkCa 15, MWC 480, and DM Tau

hal.structure.identifierLaboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux [L3AB]
hal.structure.identifierObservatoire aquitain des sciences de l'univers [OASU]
hal.structure.identifierLaboratoire d'Astrophysique de Bordeaux [Pessac] [LAB]
dc.contributor.authorDUTREY, Anne
dc.contributor.authorHENNING, Thomas
hal.structure.identifierLaboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux [L3AB]
hal.structure.identifierObservatoire aquitain des sciences de l'univers [OASU]
hal.structure.identifierLaboratoire d'Astrophysique de Bordeaux [Pessac] [LAB]
dc.contributor.authorGUILLOTEAU, S.
dc.contributor.authorSEMENOV, Dmitry
dc.contributor.authorPIÉTU, Vincent
dc.contributor.authorSCHREYER, Katharina
hal.structure.identifierLaboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux [L3AB]
hal.structure.identifierObservatoire aquitain des sciences de l'univers [OASU]
hal.structure.identifierLaboratoire d'Astrophysique de Bordeaux [Pessac] [LAB]
dc.contributor.authorBACMANN, A.
dc.contributor.authorLAUNHARDT, Ralf
dc.contributor.authorPETY, Jerome
dc.contributor.authorGUETH, Frederic
dc.date.created2006
dc.date.issued2007
dc.identifier.issn0004-6361
dc.description.abstractEnAims: To constrain the ionization fraction in protoplanetary disks, we present new high-sensitivity interferometric observations of N$_2$H$^+$ in three disks surrounding DM Tau, LkCa 15, and MWC 480. Methods: We used the IRAM PdBI array to observe the N$_2$H$^+$ J=1-0 line and applied a $\chi^2$-minimization technique to estimate corresponding column densities. These values are compared, together with HCO$^+$ column densities, to results of a steady-state disk model with a vertical temperature gradient coupled to gas-grain chemistry. Results: We report two \ndhp detections for LkCa 15 and DM Tau at the $5 \sigma$ level and an upper limit for MWC 480. The column density derived from the data for LkCa 15 is much lower than previously reported. The [N$_2$H$^+$/HCO$^+$] ratio is on the order of 0.02--0.03. So far, HCO$^+$ remains the most abundant observed molecular ion in disks. Conclusions: All the observed values generally agree with the modelled column densities of disks at an evolutionary stage of a few million years (within the uncertainty limits), but the radial distribution of the molecules is not reproduced well. The low inferred concentration of N$_2$H$^+$ in three disks around low-mass and intermediate-mass young stars implies that this ion is not a sensitive tracer of the overall disk ionization fraction.
dc.language.isoen
dc.publisherEDP Sciences
dc.subject.enMWC 480
dc.subject.enStars: circumstellar matter
dc.subject.enplanetary systems: protoplanetary disks
dc.subject.enindividual: LkCa 15
dc.subject.enDM Tau
dc.subject.enStellar PropertiesRadio-lines: stars
dc.title.enChemistry in disks I - Deep search for N$_2$H$^+$ in the protoplanetary disks around LkCa 15, MWC 480, and DM Tau
dc.typeArticle de revue
dc.subject.halPhysique [physics]/Astrophysique [astro-ph]/Cosmologie et astrophysique extra-galactique [astro-ph.CO]
dc.subject.halPlanète et Univers [physics]/Astrophysique [astro-ph]
dc.identifier.arxivastro-ph/0612534
bordeaux.journalAstronomy and Astrophysics - A&A
bordeaux.page615-623
bordeaux.volume464
bordeaux.issue2
bordeaux.peerReviewedoui
hal.identifierhal-00128299
hal.version1
hal.popularnon
hal.audienceNon spécifiée
hal.origin.linkhttps://hal.archives-ouvertes.fr//hal-00128299v1
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