Evidence spotted that explains a decades-old mystery surrounding the sun

Now the long list of possible explanations has been narrowed down thanks to data collected by NASA’s Parker Solar Probe, the fastest man-made object ever, which has repeatedly passed over the sun as it searches for clues to the so-called “coronal heating mystery.”

During the probe’s first approach to the Sun, its instruments detected sudden reversals in the direction of our star’s magnetic fields.

Scientists call such events “switchbacks” and suspect they play a role in heating the corona, primarily by releasing the magnetic energy packed inside it as it moves within the sun and into space.

“This energy has to go somewhere, and it could be contributing to heating the corona and accelerating the solar wind,” study co-author Mojtaba Akhavan-Tafti of the University of Michigan said in a statement.

The mystery of the corona’s heating comes from the fact that the Sun’s outer atmosphere, or corona, is hundreds of times hotter than the Sun’s surface, or photosphere, despite the fact that the photosphere is millions of miles closer to the Sun’s core, where the nuclear fusion that provides heat and energy to our star takes place.

Although cooler than the corona, the photosphere is responsible for the vast majority of the Sun’s light, and therefore the solar corona can only be seen when light from the photosphere is blocked by an eclipse or by using a special instrument called a coronagraph.

Akhavan-Tafti and his team examined data collected from more than a dozen orbits that Parker made around our star, looking for where the rebounds began, which is crucial to understanding their effect on the corona.

However, the desired features were not found anywhere, at least not within the corona. Instead, the probe’s data showed that rebounds are a common occurrence in the solar wind near the Sun.

Scientists believe there could still be a catalytic mechanism that contributes to heating the outer part of the Sun.

One such mechanism could be explosive collisions of chaotic magnetic field lines on the sun’s surface, Akhavan-Tafti said.

During such collisions, magnetic fields vibrate like plucked guitar strings and accelerate plasma in the solar wind to high speeds.

This can distort the magnetic waves into ripples near the Sun. But if some of these waves lose steam before they leave the Sun, their energy will be thrown into the upper layers of the Sun, heating the corona.

“The mechanisms that cause the recoils to form, and the maneuvers themselves, can heat the corona and the solar wind,” Akhavan-Tafti said in a news release.

This research refines our understanding of how the Sun works and could eventually help scientists predict, detect and prepare for solar storms.

Source: Space