It has been realized in recent years that the accretion of pebble-sized dust particles onto planetary cores is an important mode of core growth , which enables the formation of giant planets at large distances and assists planet formation in general .
The pebble accretion theory is built upon the orbit theory of dust particles in a laminar protoplanetary disk ( PPD ) .
For sufficiently large core mass ( in the “ Hill regime ” ) , essentially all particles of appropriate sizes entering the Hill sphere can be captured .
However , the outer regions of PPDs are expected to be weakly turbulent due to the magnetorotational instability ( MRI ) , where turbulent stirring of particle orbits may affect the efficiency of pebble accretion .
We conduct shearing-box simulations of pebble accretion with different levels of MRI turbulence ( strongly turbulent assuming ideal magnetohydrodynamics , weakly turbulent in the presence of ambipolar diffusion , and laminar ) and different core masses to test the efficiency of pebble accretion at a microphysical level .
We find that accretion remains efficient for marginally coupled particles ( dimensionless stopping time \tau _ { s } \sim 0.1 - 1 ) even in the presence of strong MRI turbulence .
Though more dust particles are brought toward the core by the turbulence , this effect is largely canceled by a reduction in accretion probability .
As a result , the overall effect of turbulence on the accretion rate is mainly reflected in the changes in the thickness of the dust layer .
On the other hand , we find that the efficiency of pebble accretion for strongly coupled particles ( down to \tau _ { s } \sim 0.01 ) can be modestly reduced by strong turbulence for low-mass cores .