Observations of the Formation, Development, and Structure of a Current Sheet in an Eruptive Solar Flare

TL;DR

This paper reports detailed observations of a current sheet during a major solar flare, revealing its stable thickness, high temperature, and reconnection rate consistent with theoretical models, enhancing understanding of solar eruption mechanisms.

Contribution

It provides the first detailed characterization of a current sheet in an eruptive solar flare using high-resolution AIA data, including measurements of its properties and reconnection rate.

Findings

Current sheet remains a few thousand km thick during the event.

Temperature of the current sheet ranged between 8-10 MK.

Reconnection rate estimated at 0.004-0.007, aligning with models.

Abstract

We present AIA observations of a structure we interpret as a current sheet associated with an X4.9 flare and coronal mass ejection that occurred on 2014~February~25 in NOAA Active Region 11990. We characterize the properties of the current sheet, finding that the sheet remains on the order of a few thousand km thick for much of the duration of the event and that its temperature generally ranged between $8-10\,\mathrm{MK}$. We also note the presence of other phenomena believed to be associated with magnetic reconnection in current sheets, including supra-arcade downflows and shrinking loops. We estimate that the rate of reconnection during the event was $M_{A} \approx 0.004-0.007$, a value consistent with model predictions. We conclude with a discussion of the implications of this event for reconnection-based eruption models.