X-rays and fluctuating X-winds from protostars.

Protostars emit more X-rays, hard and soft, than young Sun-like stars in more advanced stages of formation. The X-ray emission becomes harder and stronger during flares. The excess X-rays may arise as a result of the time-dependent interaction of an accretion disk with the magnetosphere of the central star. Flares produced by such fluctuations have important implications for the X-wind model of protostellar jets, for the flash-heating of the chondrules found in chondritic meteorites, and for the production of short-lived radioactivities through the bombardment of primitive rocks by solar cosmic rays.