This simulation shows the evolution of a magnetic field on the sun in response to a twisting motion applied at its base, located in the sun's visible surface or photosphere. The white field lines are initially all open, with only one end anchored in the sun and the other dangling off into space. The blue field lines all initially form closed loops. Twisting the closed field lines builds up the magnetic pressure, causing the whole structure to rise. At some point, the closed field becomes unstable and starts to buckle. This deformation leads to a reconnection event in which adjacent open and closed field lines join, unleashing magnetic energy that pushes the gas upwards, creating the high-speed jet observed by the STEREO craft.
Credit: E. Pariat, S.K. Antiochus, C.R. DeVore