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Abstract:
Magnetic reconnection takes place to change magnetic configurations in the corona on short timescales, resulting in catastrophic release of free magnetic energy into plasmas and particles in flares and coronal mass ejections. Over longer timescales and prior to the eruption, magnetic reconnection is also considered to play a crucial role in the evolution, including reconfiguration, of magnetic structures of solar eruptions. However, it has not been clear whether magnetic reconnection is a trigger or a consequence (albeit an important one) of the eruption driven by other mechanisms. Both observations and numerical simulations have fallen short of providing a definite answer to this question, and it has been increasingly questioned whether it is even meaningful to distinguish the primary or secondary roles of ideal and non-ideal instabilities. This talk reviews recent progress in observational investigations on signatures of magnetic reconnection, and properties or structures indicative of magnetic flux ropes and their evolution. Observations with improved cadence and resolutions, and in particular, with the capabilities to observe the Sun in multiple wavelengths and from multiple vantage points, allow us to reconstruct the tempo-spatial sequence of dynamic events including flares, CMEs, coronal dimmings, and various events on smaller scales, and examine the interplay between magnetic reconnection and other mechanisms during the evolution of solar active regions that finally erupt.
