Probe found the source of mysterious magnetic switchbacks on the Sun

Researchers from University College London used the Solar Orbiter probe to discover how magnetic switchbacks — unusual structures in the flow of charged particles — are born on the Sun. The results of the study were published in the journal Nature Astronomy.

The Sun constantly ejects solar wind into space — a stream of charged particles threaded with magnetic field lines. Sometimes these lines sharply bend back toward the star itself, forming so-called magnetic switchbacks. Scientists had long been unable to determine exactly where they originate. Now the answer has been found: these structures retain "imprints" of the solar surface, which can be used to trace their origin.

By analyzing the chemical composition of particles inside one such switchback, the researchers discovered an anomalously high ratio of oxygen to carbon ions accompanied by a decrease in the amount of helium. This indicated that the material had escaped from superheated closed magnetic loops in the corona — the outer layer of the Sun's atmosphere. A reconnection process had occurred: closed magnetic loops collided with open field lines and ejected superheated material into space.

Historically, astrophysics has seen a debate over two main processes capable of heating the solar atmosphere and accelerating the wind: magnetic reconnection on the one hand, and waves and turbulence on the other. Studying magnetic switchbacks helped scientists link these two ideas. It turned out that reconnection is responsible for the birth of these structures, while wave processes are responsible for their subsequent propagation.

The discovery shows that magnetic field switchbacks are not simply random glitches but rather distinctive "messages" from the Sun. They carry information about the physical processes that heat the stellar atmosphere and accelerate the solar wind. In the future, decoding such messages will help physicists more accurately predict space weather, which affects the operation of satellites and electronics on Earth.