Small-scale structures on the solar surface : the evolution of magnetic bright points

• Main Author: Hewitt, Rebecca L.
• Published: Queen's University Belfast 2016
• Subjects: 523.7
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.706972

Magnetic Bright Points (MBPs) are some of the smallest observable features on the solar surface. However, the ubiquitous nature of these features demonstrates their potential to have a great impact on the global properties of the Sun. This thesis explores their evolutionary properties and provides an in-depth study using advanced numerical simulations, high-resolution observations and state-of-the-art inversion techniques. The evolution of MBP physical properties and spectropolarimetric signatures, found in the numerical simulations, was shown consistent to the theory of convective collapse, confirming this as the formation process. In particular, a strong downflow that acts to evacuate the flux tube causing it to collapse and form the MBP was found to precede enhancements in intensity and magnetic field. The strong kG fields associated with these features showed signatures through the increasing amplitude of Stokes-V profiles and the Zeeman splitting of Stokes-I profiles throughout each evolution. The line split- ting due to the magnetic field strength of MBPs is yet to be observed, however, we have demonstrated that the high-resolution afforded by the simulations allows much more information and structure to be detected that can not yet be observed with current instrumentation. This simple view of the evolution of MBPs required observational corroboration that had so far not been provided. Hence, focus moved towards the use of high-resolution observations with the application of one of the most advanced inversion codes to infer physical properties. With a greater understanding of the reliability of our chosen inversion code, a study of 300 MBP features was carried out, revealing more complex evolutionary characteristics and uncovering two distinct groups of these features defined by their maximum magnetic field experienced. The features within each group displayed different traits supporting the distinction of them into two categories; strong MBPs and weak MBPs.