Solar jets are common transient plasma ejection phenomena in the solar atmosphere, observable across multiple wavebands including Hα, extreme ultraviolet (EUV), and X‑ray wavebands. Coronal jets, in particular, continuously transport mass and energy from the lower to the upper solar atmosphere and are widely regarded as a potential source of coronal heating and solar wind acceleration. The formation of coronal jets is primarily attributed to two driving mechanisms: magnetic reconnection and magnetoacoustic waves.

In recent years, high-resolution observations have revealed that coronal jets exhibit periodic eruption patterns. However, direct observational evidence for the driving mechanism behind these quasiperiodic coronal jets has remained elusive.

To address this gap, a research team from the Xinjiang Astronomical Observatory of the Chinese Academy of Sciences (CAS) has uncovered direct observational evidence for the quasiperiodic magnetic reconnection driving mechanism of coronal jets. The team utilized high spatiotemporal resolution observations from both space-based (SDO) and ground-based (NVST) telescopes.

The results indicate that quasiperiodic coronal jets are driven by quasiperiodic magnetic reconnection, with the reconnection process modulated by slow magnetoacoustic waves in the chromosphere.

These findings were recently published in The Astrophysical Journal.

Observations of Active Region 13468, conducted between 01:00 and 04:00 UT on October 23, 2023, revealed dozens of hot coronal jets and cool surges. The evolution of the local magnetic field showed continuous magnetic flux emergence, convergence, and cancellation in the photosphere around the jet base. Additionally, these events included continuously erupting plasmoids and two sets of quasiperiodic jets with periods of two to three minutes.

Based on high-resolution NVST observations, the researchers captured ongoing magnetic reconnection processes in the chromosphere. The jet base region exhibited a typical inverted-Y-shaped structure: bright kernels near the reconnection current sheet moved along this Y-shaped structure, and the current sheet displayed quasiperiodic brightenings. Importantly, EUV and Hα observations demonstrated a clear spatiotemporal correspondence between the quasiperiodic brightenings in the chromospheric current sheet and the coronal jets—suggesting that quasiperiodic magnetic reconnection is the driving force behind the quasiperiodic coronal jets.

Analysis showed that the jets had a quasiperiodicity of approximately two to three minutes, accompanied by significant EUV intensity enhancements and multi-peak impulsive features, indicating intermittent energy release. Meanwhile, the jet footpoints (observed in 1600 Å) displayed repetitive brightenings and outflows, suggesting that a flare-like magnetic reconnection process likely occurs in the lower solar atmosphere. The team concluded that these quasiperiodic coronal jets originate from quasiperiodic magnetic reconnection in the chromosphere.

This study provides the first direct observational evidence of a spatiotemporal correspondence between quasiperiodic coronal jets and quasiperiodic magnetic reconnection in the chromosphere. The coronal jets in this study lasted for 40 to 60 minutes while maintaining a two-to-three-minute quasiperiodicity—a combination that cannot be easily explained by magnetic reconnection alone, implying the presence of an external modulation mechanism.

The observed period is consistent with that of slow magnetoacoustic waves in the chromospheric resonant cavity, suggesting that such waves may modulate the reconnection process. Although wave-modulated reconnection is a small-scale phenomenon difficult to directly resolve with current observational facilities, the research confirms that quasiperiodic coronal jets are driven by quasiperiodic magnetic reconnection, which is in turn modulated by slow magnetoacoustic waves in the chromosphere.

This work was supported by the CAS Strategic Priority Research Program, the National Natural Science Foundation of China, among other funding sources.