  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.
