Topic: Magnetic Fields, Activity, and the Solar-Stellar Connection
From detailed imaging, and less-detailed spectroscopic observations of solar flares over the last 2 decades, we have learned much about the basic physics of these dramatic events. On the Sun, magnetic energy in the corona is built up over timescales of many hours to days, and stored on large spatial scales. Rapid restructuring of the field during the flare ‘impulsive phase’ can accelerate a coronal mass ejection, and converts magnetic energy into the kinetic energy of non-thermal particles, and into (primarily chromospheric) radiation from $\gamma$-ray to radio wavelengths. Observed stellar flares dwarf solar flares and, though spatially resolved imaging is lacking, the spectroscopy can be exquisite, sampling aspects of the flare process almost undetectable on the Sun. Flare stars may also offer different magnetic configurations for energy storage and release. The theoretical challenges in understanding flares are considerable and, in the light of recent observations, aspects of the solar ‘standard flare model’ are coming under renewed scrutiny. How does what we know about solar flares inform our understanding of stellar phenomena, and how does the much larger parameter space of stellar flares help us form a coherent picture of magnetically driven flaring?