Breakthrough revisited: investigating the requirements for growth of dust beyond the bouncing barrier
Monthly Notices of the Royal Astronomical Society
Oxford University Press
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Booth, R. A., Meru, F., Lee, M. H., & Clarke, C. J. (2018). Breakthrough revisited: investigating the requirements for growth of dust beyond the bouncing barrier. Monthly Notices of the Royal Astronomical Society, 475 (1), 167-180. https://doi.org/10.1093/mnras/stx3084
For grain growth to proceed effectively and lead to planet formation a number of barriers to growth must be overcome. One such barrier, relevant for compact grains in the inner regions of the disc, is the `bouncing barrier' in which large grains ($\sim$ mm size) tend to bounce off each other rather than sticking. However, by maintaining a population of small grains it has been suggested that cm-size particles may grow rapidly by sweeping up these small grains. We present the first numerically resolved investigation into the conditions under which grains may be lucky enough to grow beyond the bouncing barrier by a series of rare collisions leading to growth (so-called `breakthrough'). Our models support previous results, and show that in simple models breakthrough requires the mass ratio at which high velocity collisions transition to growth instead of causing fragmentation to be low, $\phi \lesssim 50$. However, in models that take into account the dependence of the fragmentation threshold on mass-ratio, we find breakthrough occurs more readily, even if mass transfer is relatively inefficient. This suggests that bouncing may only slow down growth, rather than preventing growth beyond a threshold barrier. However, even when growth beyond the bouncing barrier is possible, radial drift will usually prevent growth to arbitrarily large sizes.
planets and satellites: formation, protoplanetary discs
This work has been supported by the DISCSIM project, grant agreement 341137 funded by the European Research Council under ERC-2013-ADG and the Hong Kong RGC grant HKU 7030/11P. FM acknowledges support from the Leverhulme Trust Early Career Fellowship and the Isaac Newton Trust. This work used the DIRAC Shared Memory Processing system at the University of Cambridge, operated by the COSMOS Project at the Department of Applied Mathematics and Theoretical Physics on behalf of the STFC DiRAC HPC Facility (www.dirac.ac.uk). This equipment was funded by BIS National E-infrastructure capital grant ST/J005673/1, STFC capital grant ST/H008586/1, and STFC DiRAC Operations grant ST/K00333X/1. DiRAC is part of the National E-Infrastructure.
External DOI: https://doi.org/10.1093/mnras/stx3084
This record's URL: https://www.repository.cam.ac.uk/handle/1810/273863