  We demonstrate that magnetic reconnection is not necessary to initiate fast
CMEs. The Aly-Sturrock conjecture states that the magnetic energy of a given
force free boundary field is maximized when the field is open. This is
problematic for CME initiation because it leaves little or no magnetic energy
to drive the eruption, unless reconnection is present to allow some of the
field to escape without opening. Thus, it has been thought that reconnection
must be present to initiate CMEs. This theory has not been subject to rigorous
numerical testing because conventional MHD numerical models contain numerical
diffusion, which introduces uncontrolled numerical reconnection. We use a
quasi-Lagrangian simulation technique to run the first controlled experiments
of CME initiation in the complete lack of reconnection. We find that a flux
rope confined by an arcade, when twisted beyond a critical amount, can escape
to an open state, allowing some of the surrounding arcade to shrink and
releasing magnetic energy from the global field. This mechanism includes a true
ideal MHD instability. We conclude that reconnection is not a necessary trigger
for fast CME eruptions.

Astrophysics