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The influence of stratification upon small-scale convectively-driven dynamos

Published online by Cambridge University Press:  12 August 2011

Paul J. Bushby
Affiliation:
School of Mathematics and Statistics, Newcastle University, Newcastle upon Tyne, NE1 7RU, U.K. email: paul.bushby@ncl.ac.uk
Michael R. E. Proctor
Affiliation:
Department of Applied Mathematics and Theoretical Physics (DAMTP), University of Cambridge, Cambridge CB3 0WA, U.K. email: mrep@cam.ac.uk (MREP) and now@cam.ac.uk (NOW)
Nigel O. Weiss
Affiliation:
Department of Applied Mathematics and Theoretical Physics (DAMTP), University of Cambridge, Cambridge CB3 0WA, U.K. email: mrep@cam.ac.uk (MREP) and now@cam.ac.uk (NOW)
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Abstract

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In the quiet Sun, convective motions form a characteristic granular pattern, with broad upflows enclosed by a network of narrow downflows. Magnetic fields tend to accumulate in the intergranular lanes, forming localised flux concentrations. One of the most plausible explanations for the appearance of these quiet Sun magnetic features is that they are generated and maintained by dynamo action resulting from the local convective motions at the surface of the Sun. Motivated by this idea, we describe high resolution numerical simulations of nonlinear dynamo action in a (fully) compressible, non-rotating layer of electrically-conducting fluid. The dynamo properties depend crucially upon various aspects of the fluid. For example, the magnetic Reynolds number (Rm) determines the initial growth rate of the magnetic energy, as well as the final saturation level of the dynamo in the nonlinear regime. We focus particularly upon the ways in which the Rm-dependence of the dynamo is influenced by the level of stratification within the domain. Our results can be related, in a qualitative sense, to solar observations.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2011

References

Abbett, W. P. 2007, ApJ, 665, 1469Google Scholar
Brummell, N. H., Tobias, S. M., & Cattaneo, F. 2010, Geophys. Astrophys. Fluid Dyn., in pressGoogle Scholar
Bushby, P. J., Houghton, S. M., Proctor, M. R. E., & Weiss, N. O. 2008, MNRAS, 387, 698Google Scholar
Bushby, P. J., Proctor, M. R. E., & Weiss, N. O. 2010, in: Pogorelov, N.V., Audit, E., Zank, G.P. (eds.), Numerical Modeling of Space Plasma Flows: ASTRONUM-2009, ASP Conference Series Vol. 429 (San Francisco: ASP), p. 181Google Scholar
Cattaneo, F. 1999, ApJ, 515, L39Google Scholar
de Wijn, A. G., Stenflo, J. O., Solanki, S. K., & Tsuneta, S. 2009, Space Sci. Revs, 144, 275Google Scholar
Käpylä, P. J., Korpi, M. J., & Brandenburg, A. 2008, ApJ, 491, 353Google Scholar
Rogachevskii, I. & Kleeorin, N. 1997, Phys. Rev. E, 56, 417Google Scholar
Sánchez Almeida, J., Bonet, J. A., Viticchié, B. & Del Moro, D. 2010, ApJ, 715, L26Google Scholar
Stein, R. F., Bercik, D. & Nordlund, Å. 2003, in Pevtsov, A. A. & Uitenbroek, H. (eds.), Current Theoretical Models and Future High Resolution Solar Observations: Preparing for ATST, ASP Conference Series Vol. 286 (San Francisco: ASP), p. 121Google Scholar
Stix, M. 2004, The Sun: An Introduction (Berlin: Springer)Google Scholar
Vögler, A. & Schüssler, M. 2007, A&A, 465, L43Google Scholar