Alexander Warmuth Submitted: 13-Mar-2008 16:24
The knowledge of the volume of the thermal flare plasma is required for
determining important quantities such as thermal energy or density,
while the area of the nonthermal footpoints is essential for deriving
electron flux densities, conductive cooling rates, etc. We plan to
determine thermal and nonthermal source sizes from RHESSI HXR images as
a function of time for a larger sample of C- to X-class flares. This
will allow us to study the evolution of areas and volumes in single
events, and to see how these parameters scale with flare importance.
Since derived source sizes are sensitive to the imaging
algorithm, we are using three different methods: CLEAN as well
as the new algorithms MEM_NJIT and VIS_FORWARD. A comparison of the
results obtained with the different techniques will allow us to
determine how trustworthy the derived source sizes are, both with
respect to absolute size and temporal evolution. In a further step, we
will compare the evolution of source sizes to the evolution of the
RHESSI spectra.
Participants: Alexander Warmuth, Gottfried Mann, Henry Aurass
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