ENERGY-RELEASE IN STELLAR FLARES

Flare-like events similar to those observed on the Sun occur on many different types of stars, particularly on late K and M dwarfs. Although the physical mechanisms responsible for these events remain largely unknown, it is likely that the flare energy derives from dissipation of magnetic fields as is the case for solar flares. We review the basic observational facts that suggest an analogy between solar and stellar flares and we discuss how the different physical conditions occurring on stars may affect the application of current solar-type models to the stellar case. We show that, in spite of a qualitative agreement found between model predictions and observations, there is still no convincing evidence that stellar flares are simply scaled-up versions of solar flares. Major advances in the observations of stellar flares are required before this fundamental question can be safely addressed.