Markus J. Aschwanden Submitted: 08-Aug-2002 14:04
Thanks to the high energy resolution of the germanium-cooled
hard X-ray detectors on RHESSI we can measure the flare
source positions with a high accuracy as a function of
energy. Using a forward-fitting algorithm for image reconstruction, we can measure the systematic decrease
in the altitudes of the source centroids h(e) as a function of increasing hard X-ray energy e, as expected in the thick-target bremsstrahlung model of Brown. Spatial
modeling of the stopping depth h(e) can then be used to
invert chromospheric density models n(h). This new method
is independent of line-of-sight effects or theoretical
assumptions on hydrostatic equilibrium that plague
chromospheric density models based on UV spectroscopy.
Participants: Markus J. Aschwanden, John C. Brown, Eduard P. Kontar
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