Friday, July 5, 2013

1307.1357 (I. de Gregorio-Monsalvo et al.)

Unveiling the gas and dust disk structure in HD 163296 using ALMA observations    [PDF]

I. de Gregorio-Monsalvo, F. Ménard, W. Dent, C. Pinte, C. López, P. Klaassen, A. Hales, P. Cortés, M. G. Rawlings, K. Tachihara, L. Testi, S. Takahashi, E. Chapillon, G. Mathews, A. Juhasz, E. Akiyama, A. E. Higuchi, M. Saito, L. - Å. Nyman, N. Phillips, J. Rodń, S. Corder, T. Van Kempen
Aims: The aim of this work is to study the structure of the protoplanetary disk surrounding the Herbig Ae star HD 163296. Methods: We have used high-resolution and high-sensitivity ALMA observations of the CO(3-2) emission line and the continuum at 850 microns, as well as the 3- dimensional radiative transfer code MCFOST to model the data presented in this work. Results: The CO(3-2) emission unveils for the first time at sub-millimeter frequencies the vertical structure details of a gaseous disk in Keplerian rotation, showing the back- and the front-side of a flared disk. Continuum emission at 850 microns reveals a compact dust disk with a 240 AU outer radius and a surface brightness profile that shows a very steep decline at radius larger than 125 AU. The gaseous disk is more than two times larger than the dust disk, with a similar critical radius but with a shallower radial profile. Radiative transfer models of the continuum data confirms the need for a sharp outer edge to the dust disk. The models for the CO(3-2) channel map require the disk to be slightly more geometrically thick than previous models suggested, and that the temperature at which CO gas becomes depleted (frozen-out) from the outer regions of the disk midplane is T < 20 K, in agreement with previous studies.
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