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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 660928.0, MPI für Astronomie / Publikationen_mpia
Chemistry in disks. VIII. The CS molecule as an analytic tracer of turbulence in disks
Authors:Guilloteau, S.; Dutrey, A.; Wakelam, V.; Hersant, F.; Semenov, D.; Chapillon, E.; Henning, T.; Piétu, V.
Date of Publication (YYYY-MM-DD):2012
Journal Abbrev.:Astronomy and Astrophysics
Start Page:id.A70
Audience:Not Specified
Abstract / Description:Context. Turbulence is thought to be a key driver of the evolution of protoplanetary disks, regulating the mass accretion process, the transport of angular momentum, and the growth of dust particles. <BR /> Aims: We intend to determine the magnitude of the turbulent motions in the outer parts (>100 AU) of the disk surrounding DM Tau. <BR /> Methods: Turbulent motions can be constrained by measuring the nonthermal broadening of line emission from heavy molecules. We used the IRAM Plateau de Bure interferometer to study emission from the CS molecule in the disk of DM Tau. High spatial (1.4 × 11.4 × 1 farcs) and spectral resolution (0.126 km s-1) CS J = 3-2 images provide constraints on the molecule distribution and velocity structure of the disk. A low sensitivity CS J = 5-4 image was used in conjunction to evaluate the excitation conditions. We analyzed the data in terms of two parametric disk models, and compared the results with detailed time-dependent chemical simulations. <BR /> Results: The CS data confirm the relatively low temperature suggested by observations of other simple molecules. The intrinsic linewidth derived from the CS J = 3-2 data is much larger than expected from pure thermal broadening. The magnitude of the derived nonthermal component depends only weakly on assumptions about the location of the CS molecules with respect to the disk plane. Our results indicate turbulence with a Mach number around 0.4-0.5 in the molecular layer. Geometrical constraints suggest that this layer is located near one scale height, in reasonable agreement with chemical model predictions. Based on observations carried out with the IRAM Plateau de Bure interferometer. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain).
Free Keywords:protoplanetary disks; radio lines: planetary systems; radio lines: stars; circumstellar matter
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
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