Magnetic reconnection as the origin of X-ray jets and Hα surges on the Sun

Abstract

THE solar corona (the outermost portion of the Sun's atmosphere) is far hotter than the 'surface' (the photosphere). Recent observations of X-ray jets1a€-4 (collimated flows of plasma at temperatures of a few million degrees) suggest that magnetic reconnectiona€"the cutting of stressed magnetic field lines, which is associated with a violent release of energy, and their subsequent reconnectiona€"may be responsible for heating the corona5. But the physical relationship between the X-ray jets, microflares (localized impulsive bursts whose total energy is below the level of the standard flares) and cooler Hα surges6 (jets of gas at a temperature of about 10,000 K) has been unclear. In particular, it has been thought7 that Ha surges and X-ray jets must arise from independent processes, on the grounds that reconnection would heat any plasma to X-ray-emitting temperatures. Here we present the results of magnetohydrody-namic simulations of the reconnection process, which show that X-ray jets and Ha surges can be ejected simultaneously from microflares8,9. This suggests that the total energy associated with the microflares is much greater than previously thought, and may be significant in heating the corona.