Solar Flares

Since the 1970's, scientists have known that solar flares can produces gamma rays. EGRET even detected high-energy gamma rays from solar flares. The best example was a flare on June 11, 1991. For this particular flare, the gamma-ray energies extended into the GeV range and the emission lasted for at least 8 hours after the flare started

X-ray image of the flaring Sun from the Yohkoh satellite.

X-ray image of the flaring Sun from the Yohkoh satellite.

The production of the gamma-ray emission is believed to be caused by charged particles accelerated by the flare interacting with the surrounding solar atmosphere. GLAST will have the angular resolution to localize the gamma-ray emission and determine where the acceleration is taking place, as well as what kinds of charged-particles are involved. There may also be similarities between the particle acceleration processes in solar flares and in jets seen in AGN. Therefore the knowledge we gain from studying the flares could be also be helpful in understanding the more powerful particle accelerators that we see elsewhere in the Universe.