The role of pebble fragmentation in planetesimal formation I. Experimental study

Research output: Contribution to journalArticle


Previous work on protoplanetary dust growth shows a halt at centimeter sizes owing to the occurrence of bouncing at velocities of 0.1 m s-1 and fragmentation at velocities ≳;1 m s-1. To overcome these barriers, spatial concentration of centimeter-sized dust pebbles and subsequent gravitational collapse have been proposed. However, numerical investigations have shown that dust aggregates may undergo fragmentation during the gravitational collapse phase. This fragmentation in turn changes the size distribution of the solids and thus must be taken into account in order to understand the properties of the planetesimals that form. To explore the fate of dust pebbles undergoing fragmenting collisions, we conducted laboratory experiments on dust-aggregate collisions with a focus on establishing a collision model for this stage of planetesimal formation. In our experiments, we analyzed collisions of dust aggregates with masses between 0.7 and 91 g mass ratios between target and projectile from 1 to 126 at a fixed porosity of 65%, within the velocity range of 1.5-8.7 m s-1, at low atmospheric pressure of ∼10-3 mbar, and in free-fall conditions. We derived the mass of the largest fragment, the fragment size/mass distribution, and the efficiency of mass transfer as a function of collision velocity and projectile/target aggregate size. Moreover, we give recipes for an easy-to-use fragmentation and mass-transfer model for further use in modeling work. In a companion paper, we use the experimental findings and the derived dust-aggregate collision model to investigate the fate of dust pebbles during gravitational collapse.


  • Mohtashim Bukhari Syed
  • Jürgen Blum
  • K. Wahlberg Jansson
  • A. Johansen
External organisations
  • Technical University of Braunschweig
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Astronomy, Astrophysics and Cosmology


  • comets: general, methods: laboratory, planets and satellites: formation, protoplanetary disks, techniques: image processing
Original languageEnglish
Article number145
JournalAstrophysical Journal
Issue number2
Publication statusPublished - 2017 Jan 10
Publication categoryResearch

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Karl Wahlberg Jansson, 2017 Apr, Lund: Lund University, Faculty of Science, Department of Astronomy and Theoretical Physics. 131 p.

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