AAS 204th Meeting, June 2004
Session 18 Coronal Mass Ejections
SPD Oral, Monday, May 31, 2004, 10:00-11:30am, 704

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[18.08] Polarimetric Three-Dimensional Imaging of Coronal Mass Ejections

T. Moran (CUA and NASA/GSFC), J. Davila (NASA/GSFC)

We present the first three-dimensional reconstructions of coronal mass ejections (CMEs), which were obtained through polarization analysis of images recorded using the LASCO C2 coronagaph on board the SOHO spacecraft. The ratio of polarized-to-unpolarized electron-scattered emission is primarily a function of the angle between a radial through the scattering point and the plane-of-the-sky. Since the projected distance from sun center to the scattering point can be obtained from total brightness images, the brightness ratio measurement determines the point's distance from sun center and from the plane-of-the-sky. A topographical map is computed from the brightness ratio, from which 'top' and 'side' views of the CME are constructed. Three dimensional structure, position and velocity are computed for two CMEs, moving at 45 degrees and at 7 degrees from the Earth-Sun line. Analysis of the Earth-directed, or 'Halo' CME, shows a bilateral symmetry, indicating a loop arcade structure. The central loops are oriented vertically, while those at the ends tilt away from the arcade midplane. This work was funded by the NASA SR & T program.

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