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Figure 1: Comparison of the magnetic field at the source surface for CR 1907 ( left column) and CR 1913 ( right column) calculated from NSO and WSO magnetograms. The two neutral lines are compared in the top panel and the differences NSO-WSO are displayed in the bottom panel. |
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Figure 2:
Two different methods of computing the neutral sheet to simulate its time evolution. The sliding window method ( top panel) centers a window on concatened magnetograms with a time shift corresponding to the selected date (here three days after the begining of CR1913). The interpolation method consists in interpolating the magnetic field at the source surface between two successive Carrington maps centered at their mid-points ( bottom panel). In this example, the field map at time
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Figure 3: Comparison of the results given by the interpolation and the sliding window methods when generating the neutral line three days after the beginning of CR1913: direct comparison ( right panel) and difference ( left panel). |
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Figure 4: Illustration of the two methods of calculating the distance to the neutral sheet: analytic ( left diagram) for the simple case of a rather flat neutral line, and using an image representation for complex configurations of the neutral line ( right diagram). |
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Figure 5: Illustration of the construction of the octree representing the electron density. The division process produces nodes (intermediate stage) represented by filled circles, and leaves (final stage) represented by open circles. In this example, cubes 1 and 2 have reached their final states and are not divided further. |
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Figure 6: 3D representation of the electron density using octree compression and corresponding to the neutral sheet of CR 1913 (an iso-density surface is displayed). |
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Figure 7:
An example of a synthetic image of coronal radiance of 512 |
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Figure 8:
Synthetic images of the coronal radiance based on the Saito model of a homogeneous K corona. The left image is calculated with the analytic integration and the right image with the method of octree compression.
The |
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Figure 9:
The ratios between the equatorial radiance profiles from the octree models with different outer boundaries (from 24 to
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Figure 10: Illustration of the origin of the radiance's overestimation in the simple case of 1D sampling. The concavity of the analytic function clearly shows that the averaged sampling process tends to overestimate the electron density. |
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Figure 11: Illustration of the simulation of the temporal evolution of the neutral sheet. The top panel a) displays the individual magnetograms and the corresponding calculated neutral lines at times ti-1, ti, and ti+1. The middle panel b) illustrates the interpolation process of the neutral line at 9 equally-spaced time intervals. The octree representation of the electron density (similar to Fig. 8) is therefore updated every 3 days, and two examples corresponding to the 1st and 9th interpolations are displayed. The bottom panel c) summarizes the global process: a given octree is rotated during 3 days and then updated. |
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Figure 12: Comparison of the radial profiles of the radiance: the sheet streamer model (solid line), the axial streamer model (dotted line), and the observation of 31 March 1996 (dash-dot line). |
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Figure 13:
Examples of the tangential function Nt(d) for two values of d0 (0.2 and 0.5
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Figure 14:
Results of numerical simulation illustrating the relationships between the parameters of the tangential function for the electron density (k, d0) and for the coronal radiance (
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Figure 15:
Synoptic maps at
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Figure 16: Comparison of our model of radial function of the electron density to some published models: Van de Hulst (1950), Saito (1970), and Koutchmy & Livshits (1992). |
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Figure 17: Comparison of radiance profiles extracted at a constant longitude from observed (dashed line) and simulated (solid line) synoptic maps corresponding to CR1910 ( top panels) and CR1913 ( bottom panels). The origin of the latitude is at the south pole and the radiance is given in unit of 10-10 of the mean solar brightness. |
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Figure 18: Examples of simulated Cor-2 A and B and LASCO-C2 images. The white circle represents the solar disk. The configurations of the STEREO and SOHO spacecrafts in space are shown in the right panels). |
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Figure 19: Simulated images of the streamer belt based on the configurations of the solar corona for CR 1956 ( top panel) and CR 1885 ( bottom panel) for five heliographic latitudes of the observer. |
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Figure 20: Example of simulated polar plumes (over exposed for better visibility) combined with a streamer belt. The white circle represents the solar disk. |
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Figure 21: Simple model of a flux rope CME: geometric parameters ( left diagram) and octree representation ( right diagram). |
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Figure 22:
Temporal evolution of a simulated flux rope CME as seen by the LASCO-C2 and the Cor-2 A and B coronagraphs at angular separation of
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