On tether-cutting reconnection in sheared coronal arcades

We present preliminary numerical magnetohydrodynamic (MHD) simulation results of 3-dimensional bipolar sheared arcades and their susceptibility to eruption in a spherical geometry. The MHD simulations are run using the Adaptively Refined MHD Solver (ARMS) developed at the Naval Research Laboratory. The initially potential magnetic field is energized via highly concentrated shearing flows parallel to the polarity inversion line (PIL) of an idealized, elongated decayed active region. The tether-cutting reconnection deep in the sheared field core is generated by applying converging flows towards the active region PIL that compress magnetic fields with oppositely directed r-components together setting up a moderate guide-field reconnection scenario at the lower boundary. We present three cases that test the amount of tether-cutting reconnection required to cause the sheared field to go unstable and erupt, parameterized as the relative length of the converging flow profiles to the active region PIL. Our hypothesis is that, due to the overlying background field of the bipolar arcade, the sheared field will remain stable for a relatively small amount of tether-cutting reconnection and when the converging flows cover a substantial portion of the active region PIL, the bipolar arcade could experience a sort of eruption. We will discuss observational consequences of the eruption process and discuss future work, e.g. comparing these results with multipolar magnetic breakout eruptions.