Numerous Bidirectionally Propagating Plasma Blobs near the Reconnection Site of a Solar Eruption

Abstract

Current sheet is a common structure involved in solar eruptions. However, it is observed in minority of the events and the physical properties of its fine structures during a solar eruption are rarely investigated. Here, we report an on-disk observation that displays 108 compact, circular or elliptic bright structures, presumably plasma blobs, propagating bidirectionally along a flare current sheet during a period of $\sim$24 minutes. From extreme ultraviolet images, we have investigated the temporal variation of the blob number around the flare peak time. The current sheet connects the flare loops and the erupting filament. The width, duration, projected velocity, temperature, and density of these blobs are $\sim$1.7$\pm$0.5\,Mm, $\sim$79$\pm$57\,s, $\sim$191$\pm$81\,\kms, $\sim$10${}^{6.4\pm 0.1}$ K, and $\sim$10${}^{10.1\pm 0.3}$ cm${}^{-3}$, respectively. The reconnection site rises with a velocity of $⩽$69\,\kms. The observational results suggest that plasmoid instability plays an important role in the energy release process of solar eruptions.

Accepted by A&A, 9 pages, and 5 figures