Volume 456, Number 2, September III 2006
|Page(s)||751 - 760|
|Published online||31 August 2006|
Relations between concurrent hard X-ray sources in solar flares
Institute of Astronomy, ETH Zurich, 8092 Zurich, Switzerland e-mail: firstname.lastname@example.org
Accepted: 12 June 2006
Context.Solar flares release a large fraction of their energy into non-thermal electrons, but it is not clear where and how. Bremsstrahlung X-rays are observed from the corona and chromosphere.
Aims.We aim to characterize the acceleration process by the coronal source and its leakage toward the footpoints in the chromosphere. The relations between the sources reflect the geometry and constrict the configuration of the flare.
Methods.We studied solar flares of GOES class larger than M1 with three or more hard X-ray sources observed simultaneously in the course of the flare. The events were observed with the X-ray satellite RHESSI from February 2002 until July 2005. We used imaging spectroscopy methods to determine the spectral evolution of each source in each event. The images of all of the five events show two sources visible only at high energies (footpoints) and one source only visible at low energies (coronal or looptop source, in two cases situated over the limb).
Results. We find soft-hard-soft behavior in both, coronal source and footpoints. The coronal source is nearly always softer than the footpoints. The footpoint spectra differ significantly only in one event out of five.
Conclusions.The observations are consistent with acceleration in the coronal source and an intricate connection between the corona and chromosphere.
Key words: Sun: flares / Sun: X-rays, gamma rays / acceleration of particles
© ESO, 2006
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.