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

Syed, Mohtashim Bukhari; Blum, Jürgen; Jansson, K. Wahlberg LU and Johansen, A. LU (2017) In Astrophysical Journal 834(2).
Abstract

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... (More)

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.

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organization
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Contribution to journal
publication status
published
subject
keywords
comets: general, methods: laboratory, planets and satellites: formation, protoplanetary disks, techniques: image processing
in
Astrophysical Journal
volume
834
issue
2
publisher
University of Chicago Press
external identifiers
  • scopus:85010049743
  • wos:000393759200007
ISSN
0004-637X
DOI
10.3847/1538-4357/834/2/145
language
English
LU publication?
yes
id
18ca94fc-2e98-47aa-997d-7f7ae2096f3a
date added to LUP
2017-03-03 09:02:49
date last changed
2018-03-18 05:10:24
@article{18ca94fc-2e98-47aa-997d-7f7ae2096f3a,
  abstract     = {<p>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<sup>-1</sup> and fragmentation at velocities ≳;1 m s<sup>-1</sup>. 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<sup>-1</sup>, at low atmospheric pressure of ∼10<sup>-3</sup> 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.</p>},
  articleno    = {145},
  author       = {Syed, Mohtashim Bukhari and Blum, Jürgen and Jansson, K. Wahlberg and Johansen, A.},
  issn         = {0004-637X},
  keyword      = {comets: general,methods: laboratory,planets and satellites: formation,protoplanetary disks,techniques: image processing},
  language     = {eng},
  month        = {01},
  number       = {2},
  publisher    = {University of Chicago Press},
  series       = {Astrophysical Journal},
  title        = {The role of pebble fragmentation in planetesimal formation I. Experimental study},
  url          = {http://dx.doi.org/10.3847/1538-4357/834/2/145},
  volume       = {834},
  year         = {2017},
}