Immerse yourself in the "rhythm" of the sun! What did the solar exploration satellite "Xihe" discover?

Author: Duan Yuechu and Huang Yanhong

The sun, a star that is extremely familiar to us yet full of mystery, has always been an important object of human exploration. Recently, my country's first solar exploration satellite "Xihe" has made exciting new discoveries, providing us with precious clues to further uncover the mystery of the sun.

Nanjing University, Yunnan Astronomical Observatory of the Chinese Academy of Sciences, and the Eighth Academy of China Aerospace Science and Technology Corporation worked together to analyze the observation data of Xihe and successfully draw the world's first three-dimensional image of the rotation of the solar atmosphere. This achievement was published in the international academic journal Nature Astronomy on June 13, attracting widespread attention from the scientific community.

To understand the importance of this discovery, we must first understand some of the characteristics of stars. Stars, such as our sun, are huge spheres of plasma. Their rotation is not completely rigid, and there are differences in the rotation of different parts. As the closest star to us, the sun naturally becomes a key specimen for studying stellar rotation. From the inside to the outside, the sun is divided into the core region, the radiation zone, the convection zone, and the atmosphere. After long-term research, the scientific community has basically clarified two important laws of the sun's rotation: one is that the rotation speed changes significantly from the radiation zone to the outer convection zone; the other is that the rotation speed decreases from the equator to the poles. However, there has been no clear conclusion on what the law of rotation of the atmosphere on the surface of the sun is.

The Xihe team used the multi-spectral, full-disk, high-precision observation data collected by the satellite to finally gain a more accurate understanding of the rotation law of the solar atmosphere. They drew the world's first three-dimensional image of the rotation of the solar atmosphere, which allows us to understand the rotation of the solar atmosphere more intuitively.

Professor Ding Mingde, 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 spectrum, SiⅠ spectrum and FeⅠ spectrum. By using the inversion method, the Doppler velocity field of different layers of the solar atmosphere can be derived, which is equivalent to a full-scale scan of the entire solar atmosphere.

Other scientific research achievements of the Xihe satellite include:

- Achieved the world's first solar Hα band spectral scanning imaging: "Xihe" obtained the fine structure of the solar Hα spectral line, SiⅠ spectral line and FeⅠ spectral line, providing important data for studying the physical processes of the solar atmosphere.

- Draw the world's first multi-level Doppler velocity map of the solar atmosphere: By inverting the observation data, the Doppler velocity fields of different levels of the solar atmosphere are derived, providing a new perspective for a deeper understanding of the movement and evolution of the solar atmosphere.

- Assisting the study of solar activity and solar evolution: The observation data of Xihe will help to more accurately understand the rotation laws of the solar atmosphere, which is of great scientific significance to solar activity and solar evolution.

- Provide support for the study of the physical process of solar eruptions: "Xihe" can study the dynamic processes of the solar lower atmosphere and provide important basis for solving scientific problems such as "physical model of the whole process of energy transmission from the inside to the surface of solar eruptions".

The importance of this research lies in that it not only deepens our understanding of the rotation law of the solar atmosphere, but also provides the possibility of predicting solar activity and solar storms. For example, by studying the changing trend of the sun's rotation speed, we can predict the length of the solar activity cycle, which is crucial to ensuring the safety of the Earth's space environment.

The observation data of the Xihe satellite has been shared with the world, attracting scientists from all over the world to participate in the research. This not only reflects the importance of international cooperation, but also makes a positive contribution to the development of solar physics.

In general, the new discovery of my country's first solar exploration satellite "Xihe" has revealed a three-dimensional image of the rotation of the solar atmosphere. This achievement has not only attracted widespread attention in China, but also had a profound impact internationally. In the future, we expect the "Xihe" satellite to continue to play an important role and make greater contributions to human exploration of the mysteries of the sun and the universe.