Understanding how solar eruptions begin and evolve through the solar atmosphere

Solar eruptions are among the most powerful events occurring in our solar system and have several well-defined signatures; solar flares, observed as huge bursts of radiation, coronal mass ejections (CMEs), observed as massive bubbles of plasma hurled into space and global wave- pulses that travel through the solar atmosphere, traversing the entire solar surface in less than an hour. The exact physical processes leading to these eruptions and how they interact with the surrounding solar atmosphere remain ambiguous and subject to intensive research. Understanding these processes will provide a unique insight into the basic physics underpinning the evolution of the Sun and its atmosphere. Even more importantly, it will greatly improve our ability to predict the geo--effectiveness of CMEs (i.e., their effects on the near-Earth environment; a phenomenon known as space weather), providing the requisite warning time for protecting sensitive electronics and power distribution networks in both space-based and ground-based assets. Current models designed to explain CMEs invoke the concept of a flux rope; a twisted bundle of magnetic field which is formed in the low solar atmosphere by the reconfiguration of the solar magnetic field through the convergence, collision and subsequent disappearance of small-scale opposite polarity features. Cool, dense plasma can often become trapped within these flux ropes as they form, and are observed as filaments in chromospheric H-alpha observations. While the processes involved in the development of these filamentary flux ropes are well established, how these structures suddenly become unstable and erupt catastrophically are not as well understood. The aim of this project is to investigate the processes involved in the initiation and early evolution of solar eruptions. This will involve examining the relationship between the different forces at play in the development of the filament; the magnetic field overlying the flux rope and the mass of the filament holding it down and the magnetic pressure of the flux rope forcing it up. By identifying the point at which this equilibrium no longer holds, it may be possible to predict when a filament will erupt. The evolution of this filament through the low solar atmosphere can then be studied to understand the role played by the local and global magnetic field in determining the ultimate direction of the associated CME. This project will use observations from the Solar Dynamics Observatory, Hinode's EUV Imaging Spectrometer and the Interface Region Imaging Spectrometer