Streaming instability on different scales. I. Planetesimal mass distribution variability.

We present numerical simulations of dust clumping and planetesimal formation initiated by the streaming instability with self-gravity. We examine the variability in the planetesimal formation process by employing simulation domains with large radial and azimuthal extents and a novel approach of re-running otherwise identical simulations with different random initializations of the dust density field.We find that the planetesimal mass distribution and the total mass of dust that is converted to planetesimals can vary substantially between individual small simulations and within the domains of larger simulations. Our results show that the non-linear nature of the developed streaming instability introduces substantial variability in the planetesimal formation process that has not been previously considered and suggests larger scale dynamics may affect the process.