摘要：The streaming instability is a mechanism to concentrate solid particles into overdense
filaments that undergo gravitational collapse and form planetesimals. However, it remains
unclear how the initial mass function of these planetesimals depends on the box dimensions
of numerical simulations. To resolve this, we perform simulations of planetesimal
formation with the largest box dimensions to date, allowing planetesimals to form
simultaneously in multiple filaments that can only emerge within such large simulation
boxes. In our simulations, planetesimals with sizes between 80 km and several hundred
kilometers form. We find that a power law with a rather shallow exponential cutoff at the
high-mass end represents the cumulative birth mass function better than an integrated
power law. The steepness of the exponential cutoff is largely independent of box
dimensions and resolution, while the exponent of the power law is not constrained at the
resolutions we employ. Moreover, we find that the characteristic mass scale of the
exponential cutoff correlates with the mass budget in each filament. Together with
previous studies of high-resolution simulations with small box domains, our results
therefore imply that the cumulative birth mass function of planetesimals is consistent
with an exponentially tapered power law with a power-law exponent of approximately
−1.6 and a steepness of the
exponential cutoff in the range of 0.3–0.4.
关键词：hydrodynamics;instabilities;methods: numerical;planets and satellites: formation;protoplanetary disks
