THE RISE OF TWISTED MAGNETIC-FLUX TUBES

Sunspots are caused by the eruption of magnetic flux tubes through the solar photosphere: current theories of the internal magnetic field of the Sun suggest that such tubes must rise relatively unscathed from t he base of the convection zone. In order to understand how the structu re of the magnetic field within a buoyant flux tube affects its stabil ity as it rises, we have considered the quasi-two-dimensional rise of isolated magnetic flux tubes through an adiabatically stratified atmos phere. The magnetic field is initially helical; we have investigated a range of initial field configurations, varying the distribution and s trength of the twist of the field.