Solar flares emit sudden, strong bursts of electromagnetic radiation from the Sun’s surface and its atmosphere, and eject plasma and energetic particles into inter-planetary space. Since large solar flares can cause severe space weather disturbances affecting Earth, to mitigate their impact their occurrence needs to be predicted. However, as the onset mechanism of solar flares is unclear, most flare prediction methods so far have relied on empirical methods.

The research team led by Professor Kanya Kusano (Director of the Institute for Space-Earth Environmental Research, Nagoya University) recently succeeded in developing the first physics-based model that can accurately predict imminent large solar flares. The work was published in the journal Science on July 31, 2020.

The new method of flare prediction, called the kappa scheme, is based on the theory of “double-arc instability,” that is a magnetohydrodynamic (MHD) instability triggered by magnetic reconnection. The researchers assumed that a small-scale reconnection of magnetic field lines can form a double-arc (m-shape) magnetic field and trigger the onset of a solar flare (Figure 1). The kappa scheme can predict how a small magnetic reconnection triggers a large flare and how a large solar flare can occur.