standard model of a flare

The standard model of a flare (i.e., of a solar flare) explains them as resulting from a particular kind of magnetic reconnection of features within the Sun's magnetic field. The Sun's field produces lines that extend out through the Sun's surface, forming an arc back to the surface (often outlining visible coronal loops), typically in the general region of sunspots. In this flare model, such arched field lines have grown taller until they extend very far from the Sun and reconnection occurs, cutting the extended arching lines into a smaller arch, the rest forming a ring of lines that is disconnected from the Sun. This resulting configuration holds less magnetic-field energy, and the energy so-released accelerates electrons that have been traveling along the lines. The accelerated electrons that reach the chromosphere heat its plasma, which expands (evaporates) up into the magnetic field loops as well as between them, producing various types of EMR emission. These include thermal radiation (from material much hotter than the Sun's surface, thus much shorter wavelength than normal sunshine, with much UV and shorter wavelengths), and synchrotron radiation from the charged plasma particles passing through the magnetic field loops.