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Observing the Sun with a wide field of view sometimes catches an interesting event at an unexpected place. Hinode XRT usually observes a relatively small area of the Sun (typically the size of an active region) with high temporal and spatial resolution, but this event was caught in our synoptic full-Sun observing program, which runs twice every day.
On 5 November 2016, during our morning full-Sun observing program, XRT observed a bright arcade of loops in the North-West hemisphere. Such arcades are often observed as the aftermath of a filament eruption. But this event is special because a dark round structure, that looks like a void, is located North-East of the arcades.
It is known that a "coronal dimming" is sometimes observed around
the foot points of erupting filaments. According to the SDO/AIA movie
of this filament eruption,
the location of the void seems to correspond to the place where the
northern part of the filament started to expand rapidly. A possible
explanation would be that the coronal plasma that existed in the
void was depleted or swept away by the rapid expansion of the