Observations of Reconnection Flows in a Flare on the Solar Disk

TL;DR

This paper presents detailed observations of a solar flare on the disk, capturing all key reconnection flows simultaneously, providing clear evidence of magnetic reconnection dynamics in the solar corona.

Contribution

It provides the first comprehensive observation of all four reconnection flows in a disk flare, clarifying their dynamics and relationship to flare structures.

Findings

Symmetric reconnection inflows consistent with fast reconnection

Post-reconnection loops show cooling and deceleration

Clear evidence of plasma upflow associated with expanding magnetic fields

Abstract

Magnetic reconnection is a well-accepted part of the theory of solar eruptive events, though the evidence is still circumstantial. Intrinsic to the reconnection picture of a solar eruptive event, particularly in the standard model for two-ribbon flares ("CSHKP" model), are an advective flow of magnetized plasma into the reconnection region, expansion of field above the reconnection region as a flux rope erupts, retraction of heated post-reconnection loops, and downflows of cooling plasma along those loops. We report on a unique set of SDO/AIA imaging and Hinode/EIS spectroscopic observations of the disk flare SOL2016-03-23T03:54 in which all four flows are present simultaneously. This includes spectroscopic evidence for a plasma upflow in association with large-scale expanding closed inflow field. The reconnection inflows are symmetric, and consistent with fast reconnection, and the post-reconnection loops show a clear cooling and deceleration as they retract. Observations of coronal reconnection flows are still rare, and most events are observed at the solar limb, obscured by complex foregrounds, making their relationship to the flare ribbons, cusp field and arcades formed in the lower atmosphere difficult to interpret. The disk location and favorable perspective of this event have removed these ambiguities giving a clear picture of the reconnection dynamics.