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Disks around CQ Tau and MWC 758: dense PDR or gas dispersal?

hal.structure.identifierInstitut de RadioAstronomie Millimétrique [IRAM]
hal.structure.identifierLaboratoire d'Astrophysique de Bordeaux [Pessac] [LAB]
hal.structure.identifierLaboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux [L3AB]
hal.structure.identifierObservatoire aquitain des sciences de l'univers [OASU]
dc.contributor.authorCHAPILLON, E.
hal.structure.identifierLaboratoire d'Astrophysique de Bordeaux [Pessac] [LAB]
hal.structure.identifierLaboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux [L3AB]
hal.structure.identifierObservatoire aquitain des sciences de l'univers [OASU]
dc.contributor.authorGUILLOTEAU, S.
hal.structure.identifierLaboratoire d'Astrophysique de Bordeaux [Pessac] [LAB]
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 Grenoble [LAOG]
dc.contributor.authorDUTREY, Anne
hal.structure.identifierInstitut de RadioAstronomie Millimétrique [IRAM]
hal.structure.identifierLaboratoire d'Astrophysique de Grenoble [LAOG]
dc.contributor.authorPIÉTU, Vincent
dc.date.created2008
dc.date.issued2008
dc.identifier.issn0004-6361
dc.description.abstractEnThe overall properties of disks surrounding intermediate PMS stars (HAe) are not yet well constrained by current observations. The disk inclination, which significantly affect SED modeling, is often unknown. We attempted to resolve the disks around CQ Tau and MWC 758, to provide accurate constraints on the disk parameters, in particular the temperature and surface density distribution. We report arcsecond resolution observations of dust and CO line emissions with the IRAM array. The disk properties are derived using a standard disk model. We use the Meudon PDR code to study the chemistry. The two disks share some common properties. The mean CO abundance is low despite disk temperatures above the CO condensation temperature. Furthermore, the CO surface density and dust opacity have different radial dependence. The CQ Tau disk appears warmer, and perhaps less dense than that of MWC 758. Modeling the chemistry, we find that photodissociation of CO is a viable mechanism to explain the low abundance. The photospheric flux is not sufficient for this: a strong UV excess is required. In CQ Tau, the high temperature is consistent with expectation for a PDR. The PDR model has difficulty explaining the mild temperatures obtained in MWC 758, for which a low gas-to-dust ratio is preferred. A yet unexplored alternative could be that, despite currently high gas temperatures, CO remains trapped in grains, as the models suggest that large grains can be cold enough to prevent thermal desorption of CO. The low inclination of the CQ Tau disk, ~30^\circ, challenges previous interpretations given for the UX Ori - like luminosity variations of this star. We conclude that CO cannot be used as a simple tracer of gas-to-dust ratio, the CO abundance being affected by photodissociation, and grain growth.
dc.language.isoen
dc.publisherEDP Sciences
dc.title.enDisks around CQ Tau and MWC 758: dense PDR or gas dispersal?
dc.typeArticle de revue
dc.identifier.doi10.1051/0004-6361:200809523
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.arxiv0805.3473
bordeaux.journalAstronomy and Astrophysics - A&A
bordeaux.page565-578
bordeaux.volume488
bordeaux.peerReviewedoui
hal.identifierhal-00286457
hal.version1
hal.popularnon
hal.audienceInternationale
hal.origin.linkhttps://hal.archives-ouvertes.fr//hal-00286457v1
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