After 13 months in orbit, China's first solar exploration science and technology test satellite, "Xihe", sent good news again. On November 16, at the centennial commemoration meeting of the founding of the Chinese Astronomical Society, Ding Mingde, the chief scientist of the "Xihe" and a professor at Nanjing University, revealed that the "Xihe" made two important discoveries, namely, it measured the differential rotation of the solar photosphere and chromosphere at the same time and successfully captured a rare X1 level flare. Differential rotation refers to the phenomenon that the angular velocities of different parts of celestial bodies are different when they rotate. Differential rotation exists in most non solid celestial bodies, and the sun is one of them. "That is to say, at different latitudes of the sun, the speed of rotation is different. The equator rotates the fastest and the poles rotate the slowest." Ding Mingde explained. So, is there any difference in angular velocity within the sun? H of the sun α The (hydrogen alpha), Si I (neutral silicon atom) and Fe I (neutral iron atom) spectral lines are generated at different heights of the solar atmosphere. Where H α The spectral line is the spectral line with the strongest response of solar activity in the solar lower atmosphere α The line center of the spectral line is formed about 1300-1500 kilometers from the bottom of the photosphere, which can reflect the information of the upper solar chromosphere. The line wings reflect the information of the lower solar chromosphere and the upper photosphere; Si I spectral lines are formed about 50 to 60 kilometers from the bottom of the solar photosphere; The Fe I spectral line is formed two or three hundred kilometers from the bottom of the photosphere. The fine structure of these spectral lines can be used to invert the high-precision global chromosphere and photosphere Doppler velocity fields, record the activities in the solar atmosphere, and then study the physical process of solar activity. "H observed with the help of 'Xihe' α Spectral lines, Si I spectral lines and Fe I spectral lines, we found that the angular velocity of the solar atmosphere is different at different heights. As the sun's atmosphere rises, the sun rotates faster and faster. " Ding Mingde said in an interview with the reporter of Science and Technology Daily that in the past, many scholars in the international academic community used different detection methods and research methods to find the angular velocity difference between the solar photosphere and the chromosphere, but there is no final conclusion on what kind of law exists. For the first time, Xihe used multiple solar spectral lines to detect the rotation speed of the solar atmosphere from the photosphere to the chromosphere in space. "Due to the existence of differential rotation, the charged fluid at the bottom of the solar troposphere interacts with each other to generate a magnetic field, which floats up into the solar atmosphere, generates an active area, and gradually accumulates energy, finally forming a solar burst. Now the discovery of the law of differential rotation of the photosphere and chromosphere provides us with an important clue to reveal the formation and evolution of the solar burst." Ding Mingde said happily. Solar flare is an important manifestation of solar activity, which is a sudden and large-scale energy release process in local areas of the solar surface, causing local areas to be heated instantaneously and emitting various electromagnetic radiation. Solar flares are divided into five levels, A, B, C, M and X, and the energy released by each level increases in turn, with the X level being the largest. Humans have detected X28 solar flares. On October 2 of this year, Xihe also detected an X1 solar flare of no small scale. "With the public
Edit：wangwenting Responsible editor：xiaomai
Source：xinhuanet
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