Magnetic Flux Cancellation as the Trigger of Solar Quiet-Region Coronal Jets

TL;DR

This study shows that magnetic flux cancellation at the neutral line triggers the eruption of minifilaments, leading to quiet-region coronal jets, based on high-resolution EUV and magnetogram observations of ten events.

Contribution

It provides direct observational evidence linking flux cancellation to the initiation of quiet-region coronal jets, clarifying the eruption trigger mechanism.

Findings

Flux cancellation occurs before each jet eruption.

Minifilament eruptions are driven by flux cancellation at the neutral line.

Flux reduction between 21% and 57% is observed before eruptions.

Abstract

We report observations of ten random on-disk solar quiet region coronal jets found in high resolution Extreme Ultraviolet (EUV) images from the Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) and having good coverage in magnetograms from the SDO/Helioseismic and Magnetic Imager (HMI). Recent studies show that coronal jets are driven by the eruption of a small-scale filament (called a minifilament). However the trigger of these eruptions is still unknown. In the present study we address the question: what leads to the jet-driving minifilament eruptions? The EUV observations show that there is a cool-transition-region-plasma minifilament present prior to each jet event and the minifilament eruption drives the jet. By examining pre-jet evolutionary changes in the line-of-sight photospheric magnetic field we observe that each pre-jet minifilament resides over the neutral line between majority-polarity and minority-polarity patches of magnetic flux. In each of the ten cases, the opposite-polarity patches approach and merge with each other (flux reduction between 21 and 57%). After several hours, continuous flux cancellation at the neutral line apparently destabilizes the field holding the cool-plasma minifilament to erupt and undergo internal reconnection, and external reconnection with the surrounding-coronal field. The external reconnection opens the minifilament field allowing the minifilament material to escape outwards, forming part of the jet spire. Thus we found that each of the ten jets resulted from eruption of a minifilament following flux cancellation at the neutral line under the minifilament. These observations establish that magnetic flux cancellation is usually the trigger of quiet region coronal jet eruptions.