For the first time in history, a man-made spacecraft came in incredibly close to the Sun and made contact with it.
On April 28, 2021, NASA’s Parker Solar Probe landed in the upper part of the Sun’s atmosphere, the Crown, and flew into it. Thanks to the high-tech heat shield, he not only survived, but also made ground measurements and provided unprecedented data on the heart of the solar system.
“Parker’s solar probe ‘touching the Sun’ is a monumental moment and a truly remarkable achievement in solar science. This landmark achievement provided us with in-depth data on our solar evolution and its impact on the solar system; “Everything we learn about our star teaches us more about the rest of the stars in the universe,” said Thomas Zurbuchen, Associate Administrator at NASA.
The Parker Solar Probe was launched in 2018 and its main purpose is to study the solar corona, the same corona. During its 7-year mission, it will travel 26 times too close to the Sun, i.e. in the periphery, for which it will perform a total of seven gravitational maneuvers from Venus to get closer and closer. In April, he made his eighth appearance, which was the first time he had actually entered the crown.
During its five hours in the solar atmosphere, Parker also measured the შun’s magnetic field fluctuations and particle samples. Until now, our estimates of these characteristics have been based solely on external information.
“By flying so close to the Sun, Parker felt the environmental conditions of the Sun’s magnetic field, the crown, which we had never done before,” said Nour Rauf, a project scientist and astrophysicist.
According to him, the magnetic field data shows evidence of the presence of the crown, solar wind data and visual images. Ships can be seen flying in the crown structures, which until now we could only observe during a total solar eclipse.
The Sun has no solid surface. Its boundary is defined by the so-called. With Alfven critical surface where gravity and the Sun’s magnetic field are so weak that they can no longer hold the solar plasma.
Above this point a solar wind appears, which blows strongly through the entire solar system, so fast that the waves in the wind interrupt the Sun. What we call the “surface of the Sun” is made up of moving convective cells in the plasma, called the photosphere, which is much lower.
One of Parker’s main goals was to find out more details about Alfven’s critical surface; In particular, where it is and what its topography looks like, as we know nothing about either. Scientists estimate that the critical surface of Alfven is somewhere between 10 and 20 solar radii from the center of the Sun. Parker entered the solar corona at a solar radius of 19.7 and reached a depth of 18.4 solar radius.
Interestingly, it appears that the probe met the crown’s magnetic field sporadically, irregularly, indicating that the critical surface of the alveolus is wrinkled. At lower depths, Parker encountered a magnetic structure called a pseudo-stream, which appears to be arcuate from the Sun during a total solar eclipse. Parker’s data indicate that these structures are deformed by the critical surface of the alveolus, but we do not yet know why.
The environmental conditions in the pseudo-stream turned out to be calmer than in the surrounding atmosphere of the Sun. The particles no longer hit the ship so chaotically, and the magnetic field was much more orderly.
Parker also studied a phenomenon known as the “American Mountains” of the Sun. These are Z-shaped loops in the magnetic field of the solar wind, the place and process of which we do not know at present. The American Mountains have been known since the 1990s, but it was not until 2019 that we learned from Parker’s research that they are quite common. During the sixth flight, probe data showed that American mountains are formed from spots.
This time, Parker observed them inside the solar atmosphere, indicating that at least some of the “American Mountains” came from the lower crown.
“The structure of the regions with the American mountains coincides with the strong magnetic structure at the foot of the corona. “Some theories have already pointed this out, but now it suggests that it must be the source of the solar wind itself,” said Stuart Bailey, an astronomer at the University of California.
It is not yet known how these amazing structures are formed, but many more crossings of Parker the Snake lie ahead; After a few flights, the spacecraft will even approach the center of the Sun in the vicinity of 9.86 solar radius, and perhaps that is when we will get some answers.
“We have been observing the Sun and its crown for decades and we know that some interesting physical processes taking place there are heating and accelerating the solar wind plasma. However, we do not know anything about these processes yet, “Raufi said.
The researcher hopes that now that Parker’s solar probe is already flying directly into the crown, it will provide the long-awaited information about this mysterious region.
The research was published in Physical Review Letters.