Sharp magnetic structures from dynamos with density stratification

Sarah Jabbari, Axel Brandenburg, Nathan Kleeorin, Igor Rogachevskii

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

Recent direct numerical simulations (DNS) of large-scale turbulent dynamos in strongly stratified layers have resulted in surprisingly sharp bipolar structures at the surface. Here, we present new DNS of helically and non-helically forced turbulence with and without rotation and compare with corresponding mean-field simulations (MFS) to show that these structures are a generic outcome of a broader class of dynamos in density-stratified layers. The MFS agree qualitatively with the DNS, but the period of oscillations tends to be longer in the DNS. In both DNS and MFS, the sharp structures are produced by converging flows at the surface and might be driven in non-linear stage of evolution by the Lorentz force associated with the large-scale dynamo-driven magnetic field if the dynamo number is at least 2.5 times supercritical.

Original languageEnglish
Pages (from-to)2753-2765
Number of pages13
JournalMonthly Notices of the Royal Astronomical Society
Volume467
Issue number3
DOIs
StatePublished - 1 Jun 2017

Keywords

  • Dynamo
  • Sunspots
  • Turbulence

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