Flare-produced coronal MHD-fast-mode wavefronts and Moreton's wave phenomenon |
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| Authors: | Yutaka Uchida Martin D Altschuler Gordon Newkirk Jr |
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| Institution: | (1) Tokyo Astronomical Observatory, University of Tokyo, Mitaka, Tokyo, Japan;(2) High Altitude Observatory, National Center for Atmospheric Research, Boulder, Colorado, U.S.A.;(3) High Altitude Observatory, National Center for Atmospheric Research, Boulder, Colorado, U.S.A. |
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| Abstract: | The propagation characteristics of MHD fast-mode disturbances, which can emanate from flare regions, are computed for realistic conditions of the solar corona at the times of particular flares. The path of a fast-mode disturbance is determined by the large-scale (global) coronal distributions of magnetic field and density, and can be computed by a general raytracing procedure (eikonal equation) adapted to MHD. We use the coronal (electron) density distribution calculated from daily K-coronameter data, and the coronal magnetic field calculated under the current-free approximation from magnetograph measurements of the photospheric magnetic field. We compare the path and time-development of an MHD fast-mode wavefront emitted from the flare region (as calculated from a realistic model corona for the day of the observed Moreton wave event) with actual observations of the Moreton wave event, and find that the Moreton wave can be identified with the rapidly moving intersection of the coronal fast-mode wavefront and the chromosphere (as hypothesized in our previous paper); the directivity (anisotropic propagation), as well as other characteristics of the propagation of the Moreton wave can be successfully explained.sponsored by the National Science Foundation. |
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