The Ribbon-Like Hard X-Ray Emission in a Sigmoidal Solar Active Region
Abstract
Solar flare emissions at Halpha and EUV/UV wavelengths often appear in the form of two ribbons, which has been regarded as evidence for a typical configuration of solar magnetic reconnection. However, such a ribbon structure has rarely been observed in hard X-rays (HXRs), although it is expected as well. In this letter, we report a ribbon-like HXR source observed with the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) at energies as high as 25-100 keV during the 2005 May 13 flare. For a qualitative understanding of this unusual HXR morphology, we also note that the source active region appeared in a conspicuous sigmoid shape before the eruption and changed to an arcade structure afterward as observed with the Transition Region and Coronal Explorer (TRACE) at 171 A. We suggest that the ribbon-like HXR structure is associated with the sigmoid-to-arcade transformation during this type of reconnection.
Keywords
Cite
@article{arxiv.astro-ph/0702326,
title = {The Ribbon-Like Hard X-Ray Emission in a Sigmoidal Solar Active Region},
author = {Chang Liu and Jeongwoo Lee and Dale E. Gary and Haimin Wang},
journal= {arXiv preprint arXiv:astro-ph/0702326},
year = {2009}
}
Comments
4 pages, 4 figures, The Astrophysical Journal Letters, 2007, accepted