Since the beginning of 2024, solar activity has increased significantly, and X-class flares, solar proton events, geomagnetic storms and other strong eruption events are frequent, which is also a signal for the expected arrival of the peak of the 25th solar activity week. In particular, in just nine days from May 3 to 11, a total of 11 X-class flares and more than 60 M-class flares erupted on the sun, and the intensity and frequency of outbreaks are rare in history. With the coronal mass ejection and energetic particles produced by solar eruptions reaching the Earth, a large number of plasma clouds hit the Earth's magnetosphere, which has a significant impact on the Earth's space environment.
The National Space Weather Monitoring and Warning Center issued a red alert for geomagnetic storms at 9 a.m. on May 11: Geomagnetic storms will occur from 23 a.m. Beijing time on May 10, 2024, with the maximum level reaching the level of ultra-geomagnetic storms (Kp=9). Under the influence of geomagnetic storms, the ionosphere will be disturbed in most parts of the continent, and shortwave communication and navigation and positioning will be affected to varying degrees. A significant increase in the density of the upper atmosphere will lead to an increase in the orbital attenuation of low-orbit satellites.
Affected by this, an aurora feast came as scheduled, and from the early morning of the 11th, gorgeous auroras appeared in Heilongjiang, Xinjiang and other places on the mainland.
The aurora photographed by the HXI payload team of "Kuafu-1" on flights over Germany and Mongolia respectively (Photo by Su Yang and Li Zhentong)
And all this was "seen in the eyes" by Kuafu No. 1, and everything was "expected".
Among the sunspot groups observed by the WST telescope on the Kwafu-1 satellite in the last nine days, we can see that there is a huge sunspot activity area (No. 3663) in the northern hemisphere of the Sun, and another equally impressive sunspot activity area (No. 3664) appears in the southern hemisphere, both of which are as large as a dozen Earth radii and are covered with complex sunspots of all sizes.
The magnetic field in the direction of the line of sight in the active area 3663 (left) and 3664 (right) before the outbreak of the Great Flare. White represents the positive electrode and black represents the negative electrode.
Behind the complex sunspot group, there is a violent magnetic field. The above diagram shows the magnetic fields of the active regions 3663 and 3664 observed by the FMG instrument on Kuafu-1, respectively, and it can be seen that they all show extremely complex structures, among which there are many areas where the positive and negative electrodes are embedded in each other and "shoulder to shoulder". This complex magnetic field structure is the breeding ground for the Great Explosion.
Sure enough, these two complex "Big Mac" activity areas have staged a series of "fireworks shows" in the past 9 days, and a series of flares of the highest level, X-class, have erupted. Shown above is the image taken by the SDI telescope on the Kuafu-1, and you can see that the interior of the two active areas is constantly brightened like firecrackers, which is called the flare. And when it comes to each activity area, the "character" of their flares is very different.
Hard X-ray light curves and dynamic energy spectra (fast view) of X-class flares generated by active zone 3663 were observed by the HXI instrument carried by Kuafu-1. The higher the light curve and the darker the color of the energy spectrum, the greater the X-ray flow of the detected energy.
Active Zone 3663 is significantly more "restrained", and most of the flares it creates do not throw coronal mass ejections outward, but "digest" the energy of the magnetic field inside the active zone, resulting in a high-level flare. These flares tend to have strong hard X-ray flows, which are recorded by the HXI instrument of the Kuafu-1, as shown in the image above. Subsequently, scientists can reconstruct the light source images of these hard X-rays based on the detection results of the HXI instrument, so as to uncover the true face of these high-energy flares. Because of the "restrained" nature of this active zone, it only inflicted the first wave of solar eruption attacks (i.e., flares) on the Earth, while active zone 3664 is not so "benevolent".
Hard X-ray light curves and dynamic energy spectra (fast view) of X-class flares generated by active zone 3664 were observed by the HXI instrument carried by Kuafu-1. The higher the light curve and the darker the color of the energy spectrum, the greater the X-ray flow of the detected energy. The area of the outage in the image is that the satellite is in the shadow of the earth and is not receiving a signal from the sun.
On May 8th, immediately following the last X-Class flare in Active Area 3663, Active Area 3664 announced its succession with an X1.0-Class flare. Unlike the flare in Active Zone 3664, this flare is accompanied by a "cannonball" thrown at Earth: a coronal mass ejection. Subsequently, 3664 was not satisfied with his X1.0 flare level, and constantly challenged his upper limit, X1.1, X2.3, X4.0...... With the outbreak of large flares, a "cannonball" composed of coronal matter and magnetic fields also hit the earth one after another. Since the early morning of May 11, they have arrived on Earth one after another, creating the strongest geomagnetic storm in 20 years, which not only poses a severe test to spacecraft and communication navigation, but also presents an aurora feast for people.
The performance in Activity Area 3664 doesn't seem to be over yet. At about 9 a.m. Beijing time on May 11, an X5.8 flare erupted from the active area, setting a new flare intensity record for the active area. This eruption has produced a new wave of coronal mass ejections, which could cause sustained geomagnetic storm impacts on Earth. This shows that this area of activity is still highly active. "Kuafu-1" will join hands with other human "sun-watching weapons" to continuously monitor it.
Comparison of the HXI signal of "Kuafu-1": May 9 (left) is normal, while May 11 (right) has been mixed with a new burst of X-class flare radiation, enhanced radiation belt particles, high-energy protons from the sun, high-energy particles from geomagnetic storms, and auroras.
About the Author
Teng Weilin
Ph.D. candidate in the Multi-band Observation Research Group of Solar Activity at the Purple Mountain Observatory, Chinese Academy of Sciences. Research interests: solar eruptions and their space weather effects.
Review: Su Yang
Rotating Editor-in-Chief: Wang Ying
Editor: Wang Kechao
The reprinted content represents the author's views only
It does not represent the position of the Institute of Physics of the Chinese Academy of Sciences
If you need to reprint, please contact the original official account
Source: Purple Mountain Observatory, Chinese Academy of Sciences
Editor: Nilo