Analysis of the hydrodynamic and helioseismic effects in the photosphereduring the solar flare of July 23, 2002, observed by Michelson Doppler Imager(MDI) on SOHO, and high-energy images from RHESSI shows that these effects areclosely associated with sources of the hard X-ray emission, and that there areno such effects in the centroid region of the flare gamma-ray emission. Theseresults demonstrate that contrary to expectations the hydrodynamic andhelioseismic responses (''sunquakes") are more likely to be caused byaccelerated electrons than by high-energy protons. A series of multipleimpulses of high-energy electrons forms a hydrodynamic source moving in thephotosphere with a supersonic speed. The moving source plays a critical role inthe formation of the anisotropic wave front of sunquakes.
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