Oral Presentation

A Spatially Resolved Search for Turbulence in TW Hya

Author(s): Richard Teague (University of Michigan, USA); Stephane Guilloteau (University of Bordeaux, France); Edwin Bergin (University of Michigan, USA); Thomas Henning (Max Planck Institute for Astronomy, Germany)

Presenter: Richard Teague (University of Michigan)

Attempts to constrain the level of turbulence in a disk through the non-thermal broadening of molecular emission lines has remained inconclusive. Previous approaches all revolve around fitting a parametric model of a disk to the observations and thus require an a priori assumption about the density and temperature structure of the disk, something we have yet to well constrain. Furthermore, ALMA has demonstrated that substructure in both the gas and dust is a prominent feature of protoplanetary disks and it is therefore likely to expect significant perturbation in these properties which may confuse interpretation.

I will present an alternative approach to searching for turbulent broadening, exploiting the face-on nature of TW Hya to directly measure the temperature from molecular line emission and thus avoid assumptions about the disk structure and allowing us to account for substructure. We use observations of CO, CN and CS in an attempt to probe different vertical layers of the disk and thus provide constraints on the radial, azimuthal and vertical distribution of turbulent broadening. Furthermore, with multiple transitions of CS we are able to directly measure the temperature structure providing a much needed comparison for models.