Open AccessWhat is a flux tube? On the magnetic field topology of buoyant flux structures
Author(s) -
Cattaneo Fausto,
Brummell Nicholas H.,
Cline Kelly S.
Publication year - 2006
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2005.09741.x
Subject(s) - physics , magnetic field , magnetic flux , field line , symmetry (geometry) , flux tube , buoyancy , demagnetizing field , flux (metallurgy) , topology (electrical circuits) , l shell , classical mechanics , mechanics , geometry , magnetization , quantum mechanics , earth's magnetic field , mathematics , materials science , combinatorics , metallurgy
We study the topology of field lines threading buoyant magnetic flux structures. The magnetic structures, visually resembling idealized magnetic flux tubes, are generated self‐consistently by numerical simulation of the interaction of magnetic buoyancy and a localized velocity shear in a stably stratified atmosphere. Depending on the parameters, the system exhibits varying degrees of symmetry. By integrating along magnetic field lines and constructing return maps, we show that, depending on the type of underlying behaviour, the stages of the evolution, and therefore the degree of symmetry, the resulting magnetic structures can have field lines with one of three distinct topologies. When the x ‐translational and y ‐reflectional symmetries remain intact, magnetic field lines lie on surfaces but individual lines do not cover the surface. When the y symmetry is broken, magnetic field lines lie on surfaces and individual lines do cover the surface. When both x and y symmetries are broken, magnetic field lines wander chaotically over a large volume of the magnetically active region. We discuss how these results impact our simple ideas of a magnetic flux tube as an object with an inside and an outside, and introduce the concept of ‘leaky’ tubes.