The time evolving spatial and spectral properties of coronal X-ray sources from solar flares
Abstract
X-rays from solar flares serve as an important and direct observational tool for determining how and why electrons are accelerated. Using observations from the Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and the imaging algorithm of visibility forward fitting (VIS FWDFIT) we studied the dynamics of source spatial properties: lengths parallel to the guiding field, widths perpendicular to the guiding field and the centroid positions of three coronal X-ray loop top sources. We observed how these parameters changed in time during the evolution of each flare; before, during and after the peak X-ray emission at energies between 10-25 keV. For the first time, it was observed that the lengths and widths, and hence the volumes, of each source decreased while the X-ray emission was increasing. After the peak in X-ray emission, the volume of each source increased, mainly due to a growth in source width. For one event situated at the limb, we also observed a decrease in altitude before the peak in X-ray emission and an increase after the peak, consistent with the results of other coronal loop source observations. However, we note that the changes in loop volume were the dominant changes for each event, over any position changes. Using our imaging parameters in combination with spectral parameters (emission measure and plasma temperature), we also inferred how the number density, thermal pressure and energy density evolved during the observational time for each event. This allowed us to build a fuller picture of how the coronal region changed during the evolution of each flare. From our results, energy release occurs during the entire observational time for each event; before, during and after the peaks in X-ray emission and during both the compression and expansion phases of the loop volumes.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFMSH43B2159J
- Keywords:
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- 7509 SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY / Corona;
- 7514 SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY / Energetic particles;
- 7519 SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY / Flares;
- 7554 SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY / X-rays;
- gamma rays;
- and neutrinos