The rise of kink-unstable magnetic flux tubes in the solar convection zone

We report preliminary results of a three-dimensional simulation of the buoyant rise of a strongly twisted, kink-unstable magnetic flux tube through a gravitationally stratified layer representing the solar convection zone. The numerical calculations employ the well-known anelastic approximation, which is suitable for studying slow, subsonic dynamical processes in the pressure-dominated, high-β plasma of the solar interior. This Letter investigates the case in which the initial twist of the buoyant flux tube is sufficiently high that the e-folding growth times of the unstable kink modes are short in comparison to the rise time of the flux tube. Our simulation shows that the flux tube becomes kinked and that the top portion of the flux tube evolves into a buckled shape with the tube axis being deflected by more than 90° from its original orientation. We suggest that the emergence of this buckled flux tube can give rise to a compact magnetic bipole with polarity order inverted from Male's polarity law, similar to the configuration often seen in δ spots.