A Three-dimensional View of Turbulence: Constraints on Turbulent Motions in the HD 163296 Protoplanetary Disk Using DCO+
Abstract
Gas kinematics are an important part of the planet formation process. Turbulence influences planetesimal growth and migration from the scale of submicron dust grains through gas-giant planets. Radio observations of resolved molecular line emission can directly measure this non-thermal motion and, taking advantage of the layered chemical structure of disks, different molecular lines can be combined to map the turbulence throughout the vertical extent of a protoplanetary disk. Here we present ALMA observations of three molecules (DCO+(3-2), C18O(2-1) and CO(2-1)) from the disk around HD 163296. We are able to place stringent upper limits (v turb < 0.06c s , <0.05c s , and <0.04c s for CO(2-1), C18O(2-1), and DCO+(3-2) respectively), corresponding to α ≲ 3 × 10-3, similar to our prior limit derived from CO(3-2). This indicates that there is little turbulence throughout the vertical extent of the disk, contrary to theoretical predictions based on the magnetorotational instability and gravitoturbulence. In modeling the DCO+ emission, we also find that it is confined to three concentric rings at 65.7 ± 0.9 au, {149.9}-0.7+0.5 {au}, and 259 ± 1 au, indicative of a complex chemical environment.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- July 2017
- DOI:
- 10.3847/1538-4357/aa79f9
- arXiv:
- arXiv:1706.04504
- Bibcode:
- 2017ApJ...843..150F
- Keywords:
-
- accretion;
- accretion disks;
- protoplanetary disks;
- stars: individual: HD 163296;
- turbulence;
- Astrophysics - Earth and Planetary Astrophysics
- E-Print:
- Accepted to ApJ