The sun's "CT" has been released! my country's first solar exploration satellite "Xihe" has made new discoveries!

According to Xinhua News Agency, researchers from Nanjing University, Yunnan Astronomical Observatory of the Chinese Academy of Sciences, and the Eighth Academy of China Aerospace Science and Technology Corporation have accurately drawn the world's first three-dimensional image of the rotation of the solar atmosphere by analyzing the observation data of my country's first solar exploration satellite "Xihe". The relevant paper was published in the international academic journal "Nature Astronomy" on June 13.

Rao Shihao, the first author of the paper and a doctoral student at Nanjing University, said that a star is a huge sphere of plasma, and its rotation is not rigid, and there are differences in the rotation of different parts. As the closest star to us, the sun is an important specimen for studying stellar rotation.

"The sun can be divided into the core zone, radiation zone, convection zone and atmosphere from the inside to the outside. After decades of research, the scientific community has basically explored two important laws of the sun's rotation: one is that there is a significant change in rotation speed from the radiation zone to the outer convection zone; the second is that the rotation speed decreases from the equator to the poles." Rao Shihao said, but there is still no clear conclusion on the law of rotation of the atmosphere on the surface of the sun.

Professor Li Chuan, co-corresponding author of the paper and chief designer of the "Xihe" science and application system, told reporters that the "Xihe" team of Nanjing University used the multi-spectral, full-disk, high-precision observation data collected by the satellite to gain a more accurate understanding of the rotation laws of the solar atmosphere.

The world's first three-dimensional image of the rotation of the solar atmosphere drawn by Xihe. (Photo provided by Nanjing University)

Professor Ding Mingde, co-corresponding author of the paper and chief scientist of Xihe, said that Xihe has achieved the world's first space solar Hα band spectral scanning imaging, and simultaneously obtained the fine structure of the solar Hα spectral line, SiⅠ spectral line and FeⅠ spectral line. "Using the inversion method, we can derive the Doppler velocity field of different levels of the solar atmosphere, which is equivalent to a full-scale scan of the entire solar atmosphere. As a result, we have also obtained the world's first multi-level Doppler velocity map of the solar atmosphere."

The analysis results show that the rotation speed of each layer of the solar atmosphere shows a decreasing pattern from the equator to the poles. Moreover, the closer to the outer layer of the sun, the faster the rotation speed of the atmosphere. Li Chuan said that this is caused by the ubiquitous small-scale magnetic field structure and the "magnetic freezing" effect of the solar atmosphere.

Ding Mingde said that the faster rotation speed of the sun's outer atmosphere means that the angular momentum lost by the solar wind cannot be underestimated, which acts as a "brake" on the sun's rotation. As the sun ages, its rotation speed will gradually slow down.

According to Fang Cheng, chief scientific adviser of "Xihe" and academician of the Chinese Academy of Sciences, "Xihe" was launched into space in 2021 and is still operating stably in orbit. The relevant observation data is open to the world and shared by the Solar Science Data Center of Nanjing University, and has been used by solar physics researchers in more than 10 countries including France, Germany, the United States and Japan.

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Source: Xinhua News Agency

Editor: Wang Mengru

Proofread by Xu Lailinlin