fl227.alexander01 Posted: 3-Feb-96 Updated: 20-Sep-96 Events specified: N/A
D. Alexander, J.I Khan, L.K. Harra-Murnion, S.A. Matthews
The study of excess line widths from flaring coronal plasma is important for understanding the energy transport and redistribution in the active solar corona. The BCS on Yohkoh provides us with an excellent means of determining the thermal and non-thermal components of the resonance lines in each of its four channels. The origin of the non-thermal component is not at all well known, although it is often glibly referred to as turbulence. We plan to investigate any potential correlation between spatially resolved hard X-ray sources observed by HXT and the temporal behaviour of the non-thermal broadening. The emphasis here, as opposed to similar proposals, is to test for a source-dependent component in the non-thermal velocity. It is hoped to determine whether there is a direct response in the non-thermal broadening to the energy deposition associated with the hard X-ray emission.
Update 20-Sep-96
This work has proceeded to produce some significant results which are being prepared for publication. Studying some 20 simple compact flares we have found that in all cases for which there is good data coverage, the non-thermal line broadening peaks prior to the peak in the hard X-ray light curve. We are clearly seeing a response to the energy release in the excess widths of the BCS lines. Comparison with HXT images has not provided any new information other than confirming that these flares are compact. A extension of this study is planned to consider more complex flares with the aim of isolating the source of the non-thermal line broadening using HXT images and the time information of same. This work is being prepared as a talk for the upcoming Yohkoh anniversary meetng in Yoyogi.