Imaging sunspots using helioseismic methods

The origin of sunspots is one of the most fundamental and yet poorly understood areas in solar physics. Imaging local anomalous features in the solar interior offers a direct way to unravel the underlying physical processes of sunspots and the mechanisms behind their formation. The advent of local helioseismology in the last few years has, for the first time, made it possible to image local internal solar structures. High-resolution satellite and ground telescope data which reveal the details of the vibrations of the visible solar surface are essential in the development of local helioseismology. We are now in a position to transfer the seismic methods that have traditionally been used to study the Earth's interior to solar investigations. This interdisciplinary approach to developing seismic imaging techniques is opening up new ways of understanding the flow and other structural characteristics beneath sunspots. In this article, I review recent progress in the imaging of sunspots and the surrounding solar active regions. By highlighting the strengths of seismic methods and the challenges facing local helioseismology, I discuss some of the new research directions and possibilities that have arisen from this novel type of seismic imaging.