We report on the first observation of a single hybrid magnetic structure that contains both a pseudostreamer and a double helmet streamer. This structure was originally observed by the SWAP instrument aboard the PROBA2 satellite between 5 and 10~May~
2013. It consists of a pair of filament channels near the south pole of the sun. On the western edge of the structure, the magnetic morphology above the filaments is that of a side-by-side double helmet streamer, with open field between the two channels. On the eastern edge, the magnetic morphology is that of a coronal pseudostreamer without the central open field. We investigated this structure with multiple observations and modelling techniques. We describe the topology and dynamic consequences of such a unified structure.
The coronal magnetic field is the primary driver of solar dynamic events. Linear and circular polarization signals of certain infrared coronal emission lines contain information about the magnetic field, and to access this information, either a forwa
rd or an inversion method must be used. We study three coronal magnetic configurations that are applicable to polar-crown filament cavities by doing forward calculations to produce synthetic polarization data. We analyze these forward data to determine the distinguishing characteristics of each model. We conclude that it is possible to distinguish between cylindrical flux ropes, spheromak flux ropes, and sheared arcades using coronal polarization measurements. If one of these models is found to be consistent with observational measurements, it will mean positive identification of the magnetic morphology that surrounds certain quiescent filaments, which will lead to a greater understanding of how they form and why they erupt.
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 initia
tion 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.
