Planetesimals may form from the gravitational collapse of dense particle clumps initiated by the streaming instability. We use simulations of aerodynamically coupled gas-particle mixtures to investigate whether the properties of planetesimals formed in this way depend upon the sizes of the particles that participate in the instability. Based on three high-resolution simulations that span a range of dimensionless stopping times 6 ×10-3 ≤ τ ≤ 2, no statistically significant differences in the initial planetesimal mass function are found. The mass functions are fit by a power law, dN/ dMp ∝ M-pp, with P = 1.5-1.7 and errors of Δp ≈ 0.1. Comparing the particle density fields prior to collapse, we find hat the high-wavenumber power spectra are similarly indistinguishable, though the large-scale geometry of structures induced via the streaming instability is significantly different between all three cases. We interpret the results as evidence for a near-universal slope to the mass function, arising from the small-scale structure of streaming-induced turbulence.
- planets and satellites: formation
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science