Year: 2018
Type: article
Abstract: Small‐scale dynamo action is often held responsible for the generation of quiet Sun magnetic fields. We aim to determine the excitation conditions and saturation level of small‐scale dynamos in nonrotating turbulent convection at low magnetic Prandtl numbers. We use high‐resolution direct numerical simulations of weakly stratified turbulent convection. We find that the critical magnetic Reynolds number for dynamo excitation increases as the magnetic Prandtl number is decreased, which might suggest that small‐scale dynamo action is not automatically evident in bodies with small magnetic Prandtl numbers, such as the Sun. As a function of the magnetic Reynolds number (Rm), the growth rate of the dynamo is consistent with an Rm1/2scaling. No evidence for a logarithmic increase of the growth rate with Rm is found.
Source: Astronomische Nachrichten
Authors: P. J. Käpylä, M. J. Käpylä, A. Brandenburg
Institutions: Leibniz Institute for Astrophysics Potsdam, Max Planck Institute for Solar System Research, ReSoLVE Center of Excellence, Aalto University, Nordic Institute for Theoretical Physics, Joint Institute for Laboratory Astrophysics, Stockholm University, University of Colorado Boulder, Laboratory for Atmospheric and Space Physics, AlbaNova, KTH Royal Institute of Technology
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funder: National Science Foundation
OpenAlex ID: W2789113074