Coronae express different facets of their energy release processes in different wavelength regions. While soft X-ray and EUV emission dominates the radiative losses of the thermal plasma, hard X-ray emission (>10 keV) can be produced from non-thermal high-energy particles accelerated as a consequence of flare processes, and radio emission is often emitted from mildly relativistic electrons trap...

An open question in the field of solar and stellar astrophysics is the source of heating that causes stellar coronae to reach temperatures of millions of degrees. One possibility is that the coronae are heated by a large number of small flares. On the Sun, flares with energies as low as those of microflares are distributed with energy as a power law of the form dN dE ∝ E −α with α ≈ 1.8, and α ...

Recent developments in the study of radio emission from cool stars are reviewed. The eld of stellar radio astronomy would barely exist if active cool stars were similar to the Sun. However, many active stars appear to be fundamentally diierent from the Sun in that they possess a nonthermal corona which produces strong and steady radio emission. That is, in addition to the thermal populations at...