The True Nature of Solar Flares Revealed for the First Time

Powerful solar flares, capable of causing magnetic storms and radio disruptions on Earth, do not start with a single "explosion," but with a chain of weak disturbances that rapidly intensify and trigger an avalanche-like process. This conclusion was reached by scientists who analyzed unique data from the Solar Orbiter probe, operating under the direction of the European Space Agency. The work is published in the journal Astronomy and Astrophysics (A&A).

The observations were made during a rare close approach of the spacecraft to the Sun. During this time, Solar Orbiter recorded one of the most detailed solar flares in the history of observations. Scientists were able to track events almost 40 minutes before its peak and see how magnetic structures gradually accumulate and "unravel" in the solar corona.

According to the data, a system of thin, intertwined magnetic threads holding superheated plasma first appears in the Sun's atmosphere. These structures are unstable: individual sections of the magnetic field begin to break and immediately reconnect. Each such act of magnetic reconnection releases energy, which triggers the next one. Eventually, the process takes on an avalanche-like nature - weak events quickly develop into a powerful flare.

Scientists were particularly interested in a phenomenon they called "plasma rain." Even before the main phase of the flare and for some time afterward, streams of superheated plasma clumps rush down the Sun's atmosphere. These streams are a sign that the energy of the magnetic field is actively being transferred to the matter. According to X-ray observations, particles accelerate to speeds of 40-50% of the speed of light, making such flares potentially dangerous for space technology and astronauts.

Previously, the avalanche model was considered only as a statistical explanation for the large number of flares on the Sun and other stars. Now, for the first time, it has been shown that a single large flare can be the result of a cascade of many small events. This changes our understanding of the mechanism of energy release on the Sun and can improve space weather forecasts.

According to researchers, the data obtained is among the most important in the entire Solar Orbiter mission. They allow us to look into the "engine" of a solar flare and understand exactly how small disturbances in the magnetic field develop into enormous energy releases. In the future, scientists hope to confirm that such a mechanism is universal and works not only on the Sun but also on other active stars.