Abstract
Using HXIS data, we have studied the further development of the coronal arch extending towards the SE above active region No. 17255 in November 1980. The arch, studied originally by Švestka (1984) disappeared on 10 November (after pronounced revival), but since 9 November HXIS revealed another arch-like structure towards the SW. We have studied the development of this new structure which appeared to be most likely an arch interconnecting AR 17255 with AR 17251, located nearly 30° to the west. This interconnection revived many times during the following days with intensity varying with the activity in both active regions. We have estimated the physical characteristics in this coronal structure and compared them with observations of interconnecting loops made at lower energies by Skylab in 1973. The temperature (maximum values 7.5–14 × 106 K) and the density (1.1–5.0 × 109 cm−3) are found to be higher than in the Skylab loops (a result that could be expected because the HXIS energy range was harder than that of Skylab) and similar to the values deduced for the earlier arch system extending to the SE. However, much shorter decay times of the brightness variations indicate the presence of conduction in contrast to the SE arch in which conduction was clearly inhibited. This supports the assumption that the SE and SW coronal structures were two different phenomena.
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Presently at Delft Institute of Technology, Landbergstraat 3, 2628 CE Delft, The Netherlands.
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Fárník, F., Van Beek, H.F. & Švestka, Z. Coronal interconnection of two active regions observed in 3.5–8.0 keV X-rays. Sol Phys 104, 321–332 (1986). https://doi.org/10.1007/BF00159085
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DOI: https://doi.org/10.1007/BF00159085