fl191.tsuneta13 Posted: 18-Oct-94 Updated: 03-Apr-95, 17-Jul-95, 08-Apr-96, 27-Jan-97
1992 February 21 LDE flare and other LDE flares
S. Tsuneta
LDE flare that occurred on 1992 February 21 is one of the best example to show the involvement of magnetic reconnection in the solar flare. Initial report (Tsuneta et al., 1992, PASJ special issue) shows the temperature structure of the flare loop. The paper reports that the outer arches essentially have higher temperatures, giving one of the most convincing evidence of the reconnection.
In this new proposal, we made the same temperature analysis OUTSIDE the flare loop, and found that the shell structure in temperature extends well above and outside the bright flare loop. This strongly indicates that the reconnection point is located fairly high above the X-ray loop, and that the X-ray loop is a byproduct of the evaporation.
Further analysis will be made on the magnetic and temperature structure of the LDE flare, especially 1992 February 21 flare.
This result will be presented in the autumn annual meeting of PASJ, and a paper will be prepared.
Update 27-Jan-97
The flare of 1992 Feb 6 and other LDE events in the quiest Sun are being analyzed to clarify the magnetic configuration during the eruption.
Update 08-Apr-96
The reconnection and shock structure were determined for one flare (1992 February 21, Tsuneta, ApJ, 456, 840, 1996). We need to confirm that the conclusions derived from the flare are consistent for other LDE flares.
The analysis of the 1993 March 16 is being done.
Update 17-Jul-95
The sequel paper on 1992 February 21 event was accepted by ApJ (see fl187 final report for details), and I will proceed to the detailed analysis of the following events:
o 1991 December 2 report The initial report of this extremely interesting flare can be found in the following:
Solar flares as an ongoing magnetic reconnection process,
The magnetic and velocity fields of solar active regions,
eds., Ai, G. and Zirin, H.,
Astronomical Society of the Pacific, p239-248, 1993.
I plan to write the full paper on this event.
o Mini-cusp event recently found in active region temperature maps. The reference is as follows:
Yoshida, T., Tsuneta, S.,
Temperature structure of solar active regions,
Ap.J., in press, 1995.
Update 03-Apr-95
The following paper is being submitted to Ap.J.
STRUCTURE AND DYNAMICS OF MAGNETIC RECONNECTION IN A SOLAR FLARE S. Tsuneta
Abstract We report the detailed analysis of the temperature structure of the flare that occurred on 1992 February 21. In the decay phase of the flare, the outer loops systematically have higher temperatures, reaching the peak (12 MK) far outside the apparent bright X-ray loop where the X-ray intensity is only 1$-$5 \% of the peak. The high temperature ridges are heated by the standing isothermal slow shocks attached to the reconnection point. In between the high temperature ridges, a distinct vertical channel with temperature as low as 10$\sim$8 MK is seen at the loop top. The cool channel would be formed by the conduction cooling as the hot reconnection outflow (12 MK) traverses from the slow shock region to the loop top. The reconnection point is located 4 $\sim$ 9 $\times$ 10$^4$ km above the apparent top of the flare loop (6 $\times$ 10$^4$ km). The bright soft X-ray loops are the reconnected loops subsequently filled with evaporated plasmas.