[ Instrument Network Instrument Development ] Xie Xiaoyu, Ph.D. student of the "Sun Activity and CME Theory Research" group of the Yunnan Astronomical Observatory of the Chinese Academy of Sciences, and his collaborators, used magnetic fluid dynamics (MHD) numerical simulation to explore the disturbances generated during the solar burst. Their recent research published in the "Monthly Notices of the Royal Astronomical Society" presents important features not shown in previous simulations of volatility.
Solar bursts often produce various disturbances in the solar atmosphere, and large-scale disturbances appear as chromatic spherical Moreton waves and corona long-range ultraviolet (EUV) waves. The many peculiar features of these waves greatly enrich the research of solar physics, which not only enables people to have a more thorough understanding of the physical nature of the solar burst, but also provides a new window for diagnosing the corona plasma.
On the basis of the solar outbreak catastrophe model, Xie Xiaoyu and others explored the disturbance phenomenon in the solar burst process through MHD numerical simulation, especially the causes of some large-scale disturbances. They found that in addition to the disturbances that have occurred in past numerical experiments, there are some new phenomena. The magnetic structure moving outward during the explosion will excite a fast mode shock in front of it. The fast mode shock wave expands rapidly as it advances. As it expands to the bottom boundary, it interacts with the bottom boundary to form a Moreton wave, which in turn arouses the echo.
By comparing the simulation with the observation, Xie Xiaoyu and others first proposed the method of confirming the echo, and further showed that the echo can be observed, confirming the "true wave" nature of the EUV wave. According to the experimental results, they also found that during the evolution of the system, a part of the plasma accumulates behind the echo, forming a plasma “pile-up†(Fig.) in the low corrugated area.
The significance of this discovery is that, on the one hand, the formation height and motion characteristics of the "stacking surface" are very similar to the disturbances produced by the fast CME observed at the EUV band at a given height, and the heights appear to be basically the same; on the other hand, The “stacked surface†propagates outward behind the Moreton wave at a speed of about 1/3 of the Moreton wave, which is exactly the same as the ratio of the speed of some EUV waves to the speed of the Moreton wave. The results show that this plasma deposition surface is also a source of EUV waves. Using the data from numerical simulations, they further reconstructed images that could be "observed" in different bands. The results show that the characteristics of the "observed" EUV waves in different bands are different, which is in good agreement with the actual observations.
The work was awarded the Strategic Pilot (A) Research Project of the Chinese Academy of Sciences, the National Natural Science Foundation of China, the National Natural Science Foundation of China, the Chinese Academy of Sciences Joint Fund Project, the Yunnan Innovation Team Project, and the Yunnan Provincial Ten Thousand Plan - Yunling Scholar Project. And the support of the Chinese Academy of Sciences International Talent Program.
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