Strange Phenomenon on the Sun Imaged by Solar Orbiter for the First Time – Mystery Solved

A magnetic phenomenon known as solar yaws has been imaged by ESA/NASA’s Solar Orbiter spacecraft for the first time. The image zooms in on the yaw (blue/white feature extending to the left) as captured in the solar corona by the Metis instrument on March 25, 2022. The yaw appears to be tied to the active region seen in the Photo Central Extreme Ultraviolet Imager (right). Credit: ESA & NASA/Solar Orbiter/EUI & Metis Teams and D. Telloni et al. (2022)

With fresh data from its closest pass to the Sun so far, ESA/

” data-gt-translate-attributes=”[{” attribute=””>NASA Solar Orbiter spacecraft has found compelling clues as to the origin of solar magnetic switchbacks. The discovery points toward how their physical formation mechanism might help accelerate the solar wind.

Solar Orbiter has made the first-ever remote sensing observation consistent with a magnetic phenomenon called a solar switchback – sudden and large deflections of the solar wind’s magnetic field. The new observation provides a full view of the structure, confirming it has an S-shaped character, as predicted. Moreover, the global perspective provided by the Solar Orbiter data indicates that these rapidly changing magnetic fields can have their origin near the surface of the Sun.

A close-up view of Solar Orbiter Metis data turned into a movie shows the evolution of yaw. The sequence represents approximately 33 minutes of data taken on March 25, 2022. The bright structure forms as it propagates outward from the Sun. When it reaches its full development, it folds in on itself and acquires the distorted S-shape characteristic of a magnetic return. The structure expands at a speed of 80 km/s but the entire structure does not move at this speed. Instead, it stretches and twists. This is the first time that a magnetic return has been observed remotely. All other detections have occurred when spacecraft have flown over these disturbed magnetic regions. Credit: ESA & NASA/Solar Orbiter/Metis Teams; D. Telloni et al. (2022)

Although a number of spacecraft have already flown over these puzzling regions, in situ data only allow measurement at a single point and at a single time. Consequently, the structure and shape of the shoelace must be deduced from

” data-gt-translate-attributes=”[{” attribute=””>plasma and magnetic field properties measured at just one point.

When the German-US Helios 1 and 2 spacecraft flew close to the Sun in the mid-1970s, both probes recorded sudden reversals of the Sun’s magnetic field. These mysterious reversals were always abrupt and always temporary. They only lasted from a few seconds to a number of hours before the magnetic field switched back to its original direction.

These magnetic structures were also probed at much larger distances from the Sun by the Ulysses spacecraft in the late 1990s. Instead of a third of the Earth’s orbital radius from the Sun, where the Helios missions made their closest pass, Ulysses operated mostly beyond the Earth’s orbit.

How a solar switchback is formed infographic. Solar Orbiter has made the first ever remote sensing observation of a magnetic phenomenon called a solar ‘switchback’, proving their origin in the solar surface and pointing to a mechanism that might help accelerate the solar wind. Credit: ESA & NASA/Solar Orbiter/EUI & Metis Teams and D. Telloni et al. (2022); Zank et al. (2020)

Their number rose dramatically with the arrival of NASA’s Parker Solar Probe in 2018. This clearly indicated that the sudden magnetic field reversals are more numerous close to the Sun, and led to the suggestion that they were caused by S-shaped kinks in the magnetic field. This puzzling behavior earned the phenomenon the name of switchbacks. A number of ideas were proposed as to how these might form.

On March 25, 2022, Solar Orbiter was just a day away from a close pass of the Sun – bringing it within the orbit of planet Mercury – and its Metis instrument was taking data. Metis blocks out the bright glare of light from the Sun’s surface and takes pictures of the Sun’s outer atmosphere, known as the corona. The particles in the corona are electrically charged and follow the Sun’s magnetic field lines out into space. The electrically charged particles themselves are called a plasma.

The Sun as seen by the ESA/NASA Solar Orbiter spacecraft on March 25, 2022, one day before its closest approach of about 0.32 au, which brought it inside the orbit of planet Mercury. The central image was taken by the Extreme Ultraviolet Imager (EUI) instrument. The outer image was taken by the coronagraph Metis, an instrument that blocks out the bright light of the Sun’s surface in order to see the Sun’s faint outer atmosphere, known as the corona. The Metis image has been processed to bring out structures in the corona. This revealed the switchback (the prominent white/light blue feature at the roughly 8 o’clock position in the lower left). It appears to trace back to the active region on the surface of the Sun, where loops of magnetism have broken through the Sun’s surface. Credit: ESA & NASA/Solar Orbiter/EUI & Metis Teams and D. Telloni et al. (2022)

At around 20:39 UT, Metis recorded an image of the solar corona that showed a distorted S-shaped kink in the coronal plasma. To Daniele Telloni, National Institute for Astrophysics – Astrophysical Observatory of Torino, Italy, it looked suspiciously like a solar switchback.

Comparing the Metis image, which had been taken in visible light, with a concurrent image taken by Solar Orbiter’s Extreme Ultraviolet Imager (EUI) instrument, he saw that the candidate switchback was taking place above an active region cataloged as AR 12972. Active regions are associated with sunspots and magnetic activity. Further analysis of the Metis data showed that the speed of the plasma above this region was very slow, as would be expected from an active region that has yet to release its stored energy.

Daniele instantly thought this resembled a generating mechanism for the switchbacks proposed by Prof. Gary Zank, from the University of Alabama in Huntsville, USA. The theory looked at the way different magnetic regions near the surface of the Sun interact with each other.

ESA’s Solar Orbiter has solved the mystery of a magnetic phenomenon in the solar wind. It took the first-ever image of a ‘switchback’ in the solar corona, confirming its predicted ‘S’ shape. A rollback is defined by rapid reversals in the direction of the magnetic field. The observed reversal is related to an active region associated with sunspots and magnetic activity where there is an interaction between open and closed magnetic field lines. The interaction releases energy and sends the S-shaped disturbance out into space. The new data suggests that yaws may originate near the solar surface and may be important in understanding solar wind acceleration and heating. Credit: ESA

Near the Sun, and especially above the active regions, there are open and closed magnetic field lines. Closed lines are loops of magnetism that arc in the solar atmosphere before bending and disappearing into the Sun. Very little plasma can escape into space above these field lines, so solar wind speed tends to be slow here. Open field lines are the reverse, they emanate from the Sun and connect to the interplanetary magnetic field of the solar system. They are magnetic highways along which the plasma can flow freely and give rise to the fast solar wind.

Daniele and Gary proved that switchbacks occur when there is an interaction between a region of open field lines and a region of closed field lines. As the field lines come together, they can reconnect into more stable configurations. Much like cracking a whip, it releases energy and triggers an S-shaped disturbance moving through space, which a passing spacecraft would register as a flashback.

The Métis observation of shoelace is consistent with the strong theoretical mechanism for the production of solar magnetic shoelaces proposed in 2020 by Professor Gary Zank. The key observation was that the flashback could be seen emanating from above an active solar region. This sequence shows the chain of events that the researchers believe to take place. (a) Active regions of the Sun can exhibit open and closed magnetic field lines. The closed lines arc in the solar atmosphere before curving back towards the Sun. Open field lines connect to the interplanetary magnetic field of the solar system. (b) When an open magnetic region interacts with a closed region, the magnetic field lines can reconnect, creating an approximately S-shaped field line and producing a burst of energy. (c) As the field line responds to the reconnection and release of energy, a bend propagates outward. It’s backtracking. A similar flashback is also sent in the opposite direction, along the field line and towards the Sun. Credit: Zank et al. (2020)

According to Gary Zank, who proposed one of the theories on the origin of the shoelaces, “The first image of Métis that Daniele showed almost immediately suggested to me the caricatures we had drawn (see image above) developing the mathematical model of a shoelace.. Of course, the first image was just a snapshot and we had to temper our excitement until we used the excellent metis coverage to extract temporal information and make a more detailed spectral analysis of the images themselves The results were absolutely spectacular!

Together with a team of other researchers, they built a computer model of the behavior and found that their results looked strikingly similar to the Metis image, especially after including calculations on the elongation of the structure during its outward propagation through the solar corona. .

“I would say that this first image of a magnetic return in the solar corona revealed the mystery of their origin,” says Daniele, whose results are published in an article by Letters from the Astrophysical Journal.