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Anders Johansen. Profile picture.

Anders Johansen

Professor

Anders Johansen. Profile picture.

Gravoturbulent Planetesimal Formation: The Positive Effect of long-lived Zonal Flows

Author

  • K. Dittrich
  • H. Klahr
  • Anders Johansen

Summary, in English

Recent numerical simulations have shown long-lived axisymmetric sub- and super-Keplerian flows in protoplanetary disks. These zonal flows are found in local as well as global simulations of disks unstable to the magnetorotational instability. This paper covers our study of the strength and lifetime of zonal flows and the resulting long-lived gas over- and underdensities as functions of the azimuthal and radial size of the local shearing box. We further investigate dust particle concentrations without feedback on the gas and without self-gravity. The strength and lifetime of zonal flows increase with the radial extent of the simulation box, but decrease with the azimuthal box size. Our simulations support earlier results that zonal flows have a natural radial length scale of 5-7 gas pressure scale heights. This is the first study that combines three-dimensional MHD simulations of zonal flows and dust particles feeling the gas pressure. The pressure bumps trap particles with St = 1 very efficiently. We show that St = 0.1 particles (of some centimeters in size if at 5 AU in a minimum mass solar nebula) reach a hundred-fold higher density than initially. This opens the path for particles of St = 0.1 and dust-to-gas ratio of 0.01 or for particles of St >= 0.5 and dust-to-gas ratio 10(-4) to still reach densities that potentially trigger the streaming instability and thus gravoturbulent formation of planetesimals.

Department/s

  • Lund Observatory

Publishing year

2013

Language

English

Publication/Series

Astrophysical Journal

Volume

763

Issue

2

Document type

Journal article

Publisher

American Astronomical Society

Topic

  • Astronomy, Astrophysics and Cosmology

Keywords

  • magnetohydrodynamics (MHD)
  • planets and satellites: formation
  • protoplanetary disks

Status

Published

ISBN/ISSN/Other

  • ISSN: 0004-637X