Mind the kinematics simulation of planet-disk interactions: time evolution and numerical resolution

Kavli Affiliate: Ruobing Dong

| First 5 Authors: Kan Chen, Ruobing Dong, , ,

| Summary:

Planet-disk interactions can produce kinematic signatures in protoplanetary
disks. While recent observations have detected non-Keplerian gas motions in
disks, their origins are still being debated. To explore this, we conduct 3D
hydrodynamic simulations using the code FARGO3D to study non-axisymmetric
kinematic perturbations at 2 scale heights induced by Jovian planets in
protoplanetary disks, followed by examinations of detectable signals in
synthetic CO emission line observations at millimeter wavelengths. We advocate
for using residual velocity or channel maps, generated by subtracting an
azimuthally averaged background of the disk, to identify planet-induced
kinematic perturbations. We investigate the effects of two basic simulation
parameters, simulation duration and numerical resolution, on the simulation
results. Our findings suggest that a short simulation (e.g., 100 orbits) is
insufficient to establish a steady velocity pattern given our chosen viscosity
($alpha=10^{-3}$), and displays plenty of fluctuations on orbital timescale.
Such transient features could be detected in observations. By contrast, a long
simulation (e.g., 1,000 orbits) is required to reach steady state in kinematic
structures. At 1,000 orbits, the strongest and detectable velocity structures
are found in the spiral wakes close to the planet. Through numerical
convergence tests, we find hydrodynamics results converge in spiral regions at
a resolution of 14 cells per disk scale height (CPH) or higher. Meanwhile,
synthetic observations produced from hydrodynamic simulations at different
resolutions are indistinguishable with 0.1$^{primeprime}$ angular resolution
and 10 hours of integration time on ALMA.

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