Structure and Dynamics of Sunspots

TL;DR

This paper reviews the current understanding of sunspot structure and dynamics, emphasizing high-resolution observations of fine features and discussing recent simulation insights to better interpret their magnetic and velocity properties.

Contribution

It summarizes high-resolution observational findings of sunspot fine structures and discusses recent radiative MHD simulations to enhance understanding of their magnetic and dynamic behavior.

Findings

Detailed morphology of fine structures like light bridges and umbral dots.

Line-of-sight velocity measurements of penumbral filaments.

Magnetic field parameter analysis in sunspot features.

Abstract

The physics of Sunspots is a fascinating and demanding field of research in solar astronomy. Interaction of magnetic fields and plasma flows takes place in a tangled magnetic geometry and occurs on spatial scales that pose a continuous challenge for existing instrumentation and for the unambiguous interpretation of spectropolarimetric observations. Thus, the main properties of sunspots are well established but its fine structure is not yet fully understood. In this contribution we summarize the current knowledge of the magnetic and dynamic properties of sunspots at the photospheric level based on selected observations featuring the highest possible spatial and spectral resolution. We concentrate on light bridges, umbral dots, penumbral filaments and the notorious dark cores in penumbral filaments. We report on the morphology of the fine structure elements but mostly focus on observations of their line-of-sight velocities and magnetic field parameters. We briefly comment on results from recent radiative MHD simulations and more schematic model ideas that attempt to rationalize observations of the penumbra.