Physics

Nanoflares

Solar flare

Magnetization

Particle acceleration

Magnetic field

Solar wind

Astronomy

Magnetic energy

Flare

Magnetic reconnection

Astrophysics

Quantum mechanics

Plasma

Magnetohydrodynamics

Coronal mass ejection

Nature Astronomy

Magnetic reconnection is a universal process that powers explosive energy-release events such as solar flares, geomagnetic substorms and some astrophysical jets. A characteristic feature of magnetic reconnection is the production of fast reconnection outflow jets near the plasma Alfvén speeds1,2. In eruptive solar flares, dark finger-shaped plasma downflows moving toward the flare arcade have been commonly regarded as the principal observational evidence for such reconnection-driven outflows3,4. However, they often show a speed much slower than that expected in reconnection theories5,6, challenging the reconnection-driven energy-release scenario in standard flare models. Here we present a three-dimensional magnetohydrodynamics model of solar flares. By comparing the model predictions with the observed plasma downflow features, we conclude that these dark downflows are self-organized structures formed in a turbulent interface region below the flare termination shock where the outflows meet the flare arcade, a phenomenon analogous to the formation of similar structures in supernova remnants. This interface region hosts a myriad of turbulent flows, electron currents and shocks, crucial for flare energy release and particle acceleration. Supra-arcade downflows are dark finger-like structures associated with solar flares. Simulations now suggest that these plasma downflows form within a turbulent region that may control turbulent flows, electron currents and shockwaves.

The origin of underdense plasma downflows associated with magnetic reconnection in solar flares