| Astrophysics (Index) | About |
A stellar flare is a sudden brightening of a star, such as the Sun's solar flares. They are generally assumed to result from magnetic reconnection. They vary in brightness and energy released and the term flare star is a star that shows many flares far more substantial than historically recorded for the Sun. Some stars have periods of time when there are more and/or larger flares, and are said to be in a flaring state (or flare state) versus their other quiescent state. (These terms are also used for other astronomical bodies that emit or trigger emission of electromagnetic radiation.) A superflare or megaflare is a flare with as much as a million times the energy of a typical solar flare, having been observed with energies of 2 × 1033 to 2 × 1038 ergs. One theory regarding these exceptional flares is that the star's magnetic field interacts with that of a giant planet that has more of a magnetic field than Jupiter. The Kepler Telescope recorded some superflares.
Some stars that have extra-solar planets within their habitable zones (as far as equilibrium temperature is concerned) may still be unlikely to support life because of too-frequent flares with considerable ultraviolet.