PL: Luiz A.C. A. Schiavo, PCL: James A. McLaughlin, Gert J.J. Botha, and Natasha L.S. Jeffrey

Solar flares are among the most powerful events in the solar system, releasing vast amounts of magnetic energy stored in the Sun’s outer atmosphere, the solar corona. This energy release is driven by a fundamental process called magnetic reconnection, in which magnetic field lines reconnect in a new configuration, converting stored magnetic energy into heat, light, and the acceleration of charged particles. Solar flares produce intense bursts of radiation across the electromagnetic spectrum and can significantly influence space weather, affecting satellites, communications, and power grids on Earth. Understanding the details of how reconnection works is therefore both a fundamental physics question and a matter of practical importance.

Oscillatory reconnection is a time-dependent magnetic reconnection that occurs when a magnetic null point — a location where the magnetic field strength drops to zero — is perturbed and returns to equilibrium not smoothly, but through repeated cycles of reconnection that periodically reverse direction. Each reversal converts magnetic energy and generates heat. Until recently, studies of oscillatory reconnection were largely limited to two-dimensional models. However, the real solar corona is inherently three-dimensional, and 3D magnetic null points have a fundamentally different structure — featuring a spine axis and a fan surface — that gives rise to different reconnection dynamics. Extending our understanding of oscillatory reconnection into 3D is therefore essential for building a realistic picture of how energy is released in the solar atmosphere.

In our recent study (Schiavo et al. 2025), we demonstrated for the first time that 3D oscillatory reconnection undergoes multiple reconnection cycles. We found that the period of oscillation is constant over time and is independent of the strength of the initial perturbation that triggers the phenomenon. The oscillation period is linked to the plasma properties at the null point (magnetic field strength, density, temperature), which opens the possibility of using it as a diagnostic tool for coronal seismology, enabling the inference of fundamental plasma properties in the vicinity of 3D null points from observations. For further details, see Schiavo, Botha & McLaughlin (2025), ApJ, 993, 239, DOI: 10.3847/1538-4357/ae09ad.

Figure: Magnetic field lines illustrating the 3D null point structure with its characteristic spine-fan topology. Lines are coloured by the heating generated through magnetic reconnection, ranging from blue (low) to red (high).