ESA/NASA’s Solar Orbiter spacecraft used new data from previous closest approaches to the Sun to discover compelling clues about the origin of the Sun’s magnetic serpentinite. This discovery shows how the physical mechanism of its formation helps accelerate the solar wind.
The Solar Orbiter made the first-ever remote sensing observations consistent with a magnetic phenomenon called solar switchback. This is a sudden large deflection of the magnetic field of the solar wind. New observations provide a complete overview of the structure and confirm that it has the S-shaped features as predicted. Moreover, the full picture of the Solar Orbiter data suggests that these rapidly changing magnetic fields may be originating near the surface of the Sun.
A close-up of the Solar Orbiter Metis data converted to video shows the development of the Serpentine. This sequence represents approximately 33 minutes of data recorded on March 25, 2022. Bright structures are forming as they spread outward from the Sun. When fully deployed, it springs back on itself, exhibiting the distorted S-shaped character of the magnetic switchback. The structure is inflating at a speed of 80 km/s, but the entire structure is not moving at that speed. Instead, it stretches and distorts. This is the first time remote magnetic switchback has been observed. All other detections occurred when the spacecraft passed through these disturbed magnetic regions. Credit: ESA & NASA/Solar Orbiter/Metis Teams; D. Terroni et al. (2022)
Many spacecraft have passed through these enigmatic regions in the past, but in-situ data only allow measurements at a single point in time. Therefore, the structure and shape of the hairpin must be derived from the plasma and magnetic field properties measured at only one point.
When the German and American space probes Helios 1 and 2 flew near the Sun in his mid-1970s, both probes recorded a sudden reversal of the Sun’s magnetic field. These inexplicable reversals are always sudden and always temporary. It lasted only seconds to hours before the magnetic field returned to its original direction.
These magnetic structures were also studied far from the Sun by the Ulysses spacecraft in the late 1990s. Instead of being one-third the Earth’s orbital radius from the Sun, Ulysses operated primarily outside Earth’s orbit because the Helios mission passed closest.
That number increased dramatically with the arrival of his NASA’s Parker Solar Probe in 2018. This clearly indicates that the abrupt magnetic field reversals are more numerous near the Sun, leading to the assumption that they were caused by her S-shaped twist in the Sun’s magnetic field. This inexplicable behavior has led to the phenomenon becoming known as the Serpentine. Several ideas have been proposed as to how this could occur.
On March 25, 2022, the Solar Orbiter entered orbit around Mercury just one day after its proximity flyby of the Sun, with the Metis instrument collecting data. Metis filters out the glare on the sun’s surface and images the sun’s outer atmosphere, known as the corona. The coronal particles are electrically charged and travel into space along the Sun’s magnetic field lines. The charged particles themselves are called plasma.
At about 20:39 UT, Metis acquired an image of the solar corona, revealing her distorted S-shaped twist in the coronal plasma. To Daniele Terroni of the National Institute of Astrophysics (Astrophysical Observatory in Turin, Italy), it looked suspiciously like a solstice. Comparing the Metis image taken in visible light with the simultaneous image taken by the Solar Orbiter’s Extreme Ultraviolet Imager (EUI) instrument, he found the candidate return to be over the active region cataloged as AR 12972. confirmed. Active areas are associated with sunspots and magnetic activity. Further analysis of the Metis data showed that the velocity of the plasma in this region was very slow.
Daniele immediately thought that this was similar to the serpentinite formation mechanism proposed by Professor Gary Zank of the University of Alabama in Huntsville, USA. This theory studied how various magnetic regions near the surface of the Sun interact with each other.
ESA’s Solar Orbiter has solved the mystery of magnetic phenomena in the solar wind. It captured the first-ever image of a ‘return’ of the solar corona, confirming the predicted ‘S’ shape. Switchback is defined by a quick flip in the direction of the magnetic field. The observed switchbacks are associated with active regions associated with sunspots and magnetic activity, where there is an interaction between open and closed field lines.The interaction releases energy and sends an S-shaped perturbation into space. New data suggest that serpentinite may be forming near the surface of the Sun and may be important in understanding solar wind acceleration and warming. Photo credit: ESA
In areas close to the Sun and particularly active, there are open and closed magnetic field lines. A closed line is a magnetic loop, which loops and bulges into the Sun’s atmosphere before returning to the Sun. Above these magnetic field lines, very little plasma can escape into space, so the solar wind tends to slow down here. The open magnetic field lines emanating from the Sun and connecting to the solar system’s interplanetary magnetic field are reversed. They are magnetic highways where plasma flows freely and produces high-velocity solar winds.
Daniele and Gary proved that switchbacks occur when there is an interaction between a region of open and closed field lines. As the magnetic field lines get closer together, they can reconnect into a more stable configuration. Much like a cracking whip, this releases energy and causes an S-shaped disturbance that propagates into space. This is recorded as a turn by a passing spacecraft.
According to Gary Zank, who put forward one of the theories about the origin of the serpentine, “Almost immediately, the first Metis photo Daniele showed me was taken while I was developing a mathematical model of the serpentine. (See image above.) Of course, the first image is just a snapshot, taking advantage of Metis’ excellent coverage to extract temporal information. But I had to curb my enthusiasm until I performed a more detailed spectral analysis of the image itself.The results were really impressive!”
Together with a team of other researchers, they built a computer model of the behavior, specifically after including calculations of how the structure stretches outward as it propagates through the solar corona, and their results. was found to be very similar to the Metis image. “We can say that this first image of magnetic reversal in the solar corona has revealed the mystery of its origin,” says Daniel, whose findings were published in an article in the Journal of Astrophysics Letters.
By understanding serpentinite, solar physicists can take a step forward in understanding the details of how the solar wind accelerates and heats away from the sun. , we often record the local acceleration of the solar wind.
“The next step is to statistically link the serpentine observed in situ with the region of origin of the Sun,” says Daniele. In other words, fly a spacecraft through a reversal of magnets and see what happens on the surface of the Sun. It doesn’t mean you have to. It could be another spacecraft like the Parker Solar Probe. As long as the in situ data and his remote sensing data match, Daniele can make the associations.
“This is exactly what we wanted from the Solar Orbiter,” says Daniel Muller, ESA project scientist for the Solar Orbiter. “With each orbit, we get more data from a series of 10 instruments. Based on these results, we refine the planned observations for the Solar Orbiter’s next encounter with the Sun. and understand how the Sun connects to the wider magnetic environment of the Solar System.This was the first-ever close flyby to the Sun for a Solar Orbiter, so many more exciting results are expected. increase.”
The Solar Orbiter’s next proximity flyby to the Sun will be at 0.29 times her distance from the Earth to the Sun, again within Mercury’s orbit. It’s October 13th. Earlier this month, on September 4th, the Solar Orbiter embarked on a gravity-assisted flyby of Venus to adjust its orbit around the Sun. Subsequent Venus flybys will begin to increase the inclination of the spacecraft’s orbit, allowing access to the higher latitude (more polar) regions of the Sun.