Flux Separation in Photospheric Magnetoconvection
Abstract
Numerical experiments on three-dimensional magnetoconvection in a stratified compressible layer yield results that can now be compared with the high resolution observations of granulation and intergranular magnetic fields obtained at La Palma, and related to the slender loops revealed by TRACE. As the imposed magnetic field strength is decreased there is a transition from small-scale plumes, in the magnetically dominated regime, to large-scale vigorous plumes when the field is dominated by the motion. In the intermediate regime magnetic flux separates from the motion, so that there are almost field-free regions, with clusters of vigorous plumes, surrounded by regions where the Lorentz force is strong enough to control the dynamics. There is a range of field strengths where either small-scale plumes or flux-separated solutions can persist, depending on initial conditions for the computation. The patterns revealed in these calculations can be related to convection in sunspot umbrae (where there is a strong vertical field, and the appearance of umbral dots, to the formation of plage regions and to the behaviour of intergranular fields in the quiet Sun. In the weak field limit, turbulent convection is able to act as a dynamo and to maintain a disordered field.
- Publication:
-
Recent Insights into the Physics of the Sun and Heliosphere: Highlights from SOHO and Other Space Missions
- Pub Date:
- 2001
- Bibcode:
- 2001IAUS..203..219W