High-resolution studies of dynamic processes in the sunspot umbra: Preparing for the era of the Daniel K. Inouye Solar Telescope

Sunspots are areas of reduced temperature on the surface of the sun that appear as dark spots relative to the surrounding regions. They are the result of concentrated magnetic fields and can be associated with magnetically active regions that produce space weather events like solar flares and coronal mass ejections (CMEs). The study of sunspot dynamics and evolution is an important area of research in the field of solar physics. Occasionally, regions of brighter material cross the dark center of the sunspot (known as the umbra) to form what is called a 'light bridge'. This proposal will use the New Solar Telescope (NST) operated by the PI's institution along with satellite-based data to study the three dimensional structure and magnetic fields associated with these light bridges. The proposed research will support the training of the next generation of solar scientists. The PI will involve both a PhD graduate student and an undergraduate summer student in the proposed research.

This proposal will investigate the dynamics of light bridges observed in the umbra of sunspots and the associated activity in the chromosphere, the corona, and the transition region between the two. This research is motivated by the capability to make high-resolution observations of sunspots using the NST. Targeted observations will study the fine-scale structure of the chromosphere and the transition region above sunspots. Phenomena such as umbral jets, dynamic fibrils, and structured up-flows seen in the chromosphere and the transition region suggest that the dynamics are relatively unexplored and not well understood. The proposal describes four major goals of the work including: 1) measuring and understanding the dynamics magnetic fields in sunspot light bridges, 2) studying the shape of anomalous Stokes profiles in sunspot light bridges and determining their roles in triggering energetic events, 3) investigating the connection between photospheric dynamics and chromospheric/coronal outflows, and 4) studying the spatial structure, dynamics, and spectral properties of umbral flashes and spikes. The work outlined in the proposal will provide important preparatory science beneficial to the science planning and success of the Daniel K. Inouye Solar Telescope (DKIST).