Long-range magnetic couplings between solar flares and coronal mass ejections observed by SDO and STEREO

The combination of SDO and STEREO observations enables us to view much of the solar surface and atmosphere simultaneously and continuously. These near‐global observations often show near‐synchronous long‐distance interactions between magnetic domains that exhibit flares, eruptions, and frequent minor forms of activity. Here we analyze a series of flares, filament eruptions, coronal mass ejections, and related events which occurred on 1–2 August 2010. These events extend over a full hemisphere of the Sun, only two‐thirds of which is visible from the Earth's perspective. The combination of coronal observations and global field modeling reveals the many connections between these events by magnetic field lines, particularly those at topological divides. We find that all events of substantial coronal activity, including those where flares and eruptions initiate, are connected by a system of separatrices, separators, and quasi‐separatrix layers, with little activity within the deep interiors of domains of connectivity. We conclude that for this sequence of events the evolution of field on the hemisphere invisible from Earth's perspective is essential to the evolution, and possibly even to the initiation, of the flares and eruptions over an area that spans at least 180 degrees in longitude. Our findings emphasize that the search for the factors that play a role in the initiation and evolution of eruptive and explosive phenomena, sought after for improved space weather forecasting, requires knowledge of much, if not all, of the solar surface field. Key Points Direct magnetic connections are shown to exist in a series of flares and CMEs These connections are part of the topological skeleton of the global field Field on the far side of the Sun is argued to be involved in frontside activity