Reporters learned from the National Astronomical Observatory of the Chinese Academy of Sciences on the 2nd that based on the observation data of Guo Shoujing Telescope and Kepler Space Telescope, Chinese astronomers found that the earliest known thin disk stars in the Milky Way are about 9.5 billion years old. This provides an important observation basis for a deep understanding of the early formation and evolution history of the galactic thin disk. Relevant research results were published in the Monthly Journal of the Royal Astronomical Society. Astronomers generally believe that the main characteristic structures of the Milky Way Galaxy include the central nuclear sphere, the silver disk and the silver halo. Among them, the silver disk also includes thick disk and thin disk. The stars of thick disk form earlier than the stars of thin disk, that is, the thin disk is younger than the thick disk. The formation of the thin disk is a very important event in the Milky Way Galaxy in the past 8 billion years. So, what exactly happened when thin and thick disks formed? When was the earliest thin disk star formed? "These problems have been puzzling astronomers. The key to solving these problems is to obtain accurate age samples of silver stars," said Wu Yaqian, the first author of the paper and an associate researcher of the National Astronomical Observatory of the Chinese Academy of Sciences. Astroseismology is considered to be one of the most accurate ways to obtain the age of stars. Because of the relatively high brightness of the red giant stars, astronomers generally use these red giant stars distributed on the silver disk as probes to trace to the far side of the silver disk. In this study, researchers accurately measured the age of 5306 red giant stars. On this basis, researchers have distinguished stars with thin and thick disks by chemical methods, and systematically studied the age distribution of silver disk stars with thin disks, and found that the age of the oldest thin disk stars is about 9.5 billion years. "This result is consistent with the theoretical expectation of the silver disk 'double falling' model. At the same time, the galactic thick disk is still forming stars within this time, which indicates that there is a common time window for the formation of galactic thin disk and thick disk stars." Wu Yaqian explained. In addition, this study also found that the metal abundance distribution and spatial distribution of the first batch of thin disk stars are relatively wide, which indicates that the inner and outer disk stars in the thin disk stars may be formed at the same time. (Xinhua News Agency)