Simultaneous Observation of Reconnection Inflow and Outflow Associated with the 2010 August 18 Solar Flare

TL;DR

This study presents simultaneous observations of magnetic reconnection inflow and outflow during a solar flare, revealing plasma blobs and estimating the reconnection rate, providing insights into the reconnection process.

Contribution

First simultaneous EUV observations of inflow and outflow in a solar flare, including plasma blob dynamics and reconnection rate estimation.

Findings

Plasma blobs ejected bidirectionally at 220-460 km/s (outflow) and 250-280 km/s (inflow).

Reconnection rate varied from 0.20 to 0.055 during the flare.

Plasma blobs merged before ejection, indicating plasmoid formation.

Abstract

We report the simultaneous extreme ultraviolet observation of magnetic reconnection inflow and outflow in a flare on 2010 August 18 observed by the Atmospheric Imaging Assembly on board the {\it Solar Dynamics Observatory}. We found that during the rise phase of the flare, some plasma blobs appeared in the sheet structure above the hot loops. The plasma blobs were ejected bidirectionally along the sheet structure (outflow), at the same time as the threads visible in extreme ultraviolet images moved toward the sheet structure (inflow). The upward and downward ejection velocities are 220-460 km s$^{-1}$ and 250-280 km s$^{-1}$, respectively. The inflow speed changed from 90 km s$^{-1}$ to 12 km s$^{-1}$ in 5 minutes. By using these velocities, we estimated the nondimensional reconnection rate, which we found to vary during this period from 0.20 to 0.055. We also found that the plasma blobs in the sheet structure collided or merged with each other before they were ejected from the sheet structure. We hypothesize that the sheet structure is the current sheet and that these plasma blobs are plasmoids or magnetic islands, which could be important for understanding the dynamics of the reconnection region.