Millimeter gap contrast as a probe for turbulence level in protoplanetary disks

Turbulent motions are believed to regulate angular momentum transport and influence dust evolution in protoplanetary disks. Measuring the strength of turbulence is challenging through gas line observations because requirement for high spatial spectral resolution data, an exquisite determination temperature. In this work, taking well-known HD 163296 disk as example, we investigated contrast gaps identified continuum images a probe level turbulence. With self-consistent radiative transfer models, simultaneously analyzed radial brightness profiles along major minor axes, azimuthal B67 B100 rings. By fitting all gap contrasts measured from these profiles, constrained gas-to-dust scale height ratio Λ be 3.0 −0.8 +0.3 , 1.2 −0.1 +0.1 ≥ 6.5 D48, B67, regions, respectively. The varying ratios indicate that degree settling changes with radius. inferred values translate into αturb < 3 × 10−3 D48 which consistent previous upper limits set by observations. However, turbulent ring strong ∼ 10−2. Due degeneracy between depth surface density drops, D86 region not constrained.