Evidence for Universality in the Initial Planetesimal Mass Function

Jacob B. Simon, Philip J. Armitage, Andrew N. Youdin, Rixin Li

Research output: Contribution to journalArticlepeer-review

73 Scopus citations


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.

Original languageEnglish (US)
Article numberL12
JournalAstrophysical Journal Letters
Issue number2
StatePublished - Oct 1 2017


  • hydrodynamics
  • instabilities
  • planets and satellites: formation

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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