[Scientific Research Progress] The scientific researchers of Shanghai Observatory revealed that the galaxy occurred in the long -distance Lord and the incident

Recently, the Shanghai Academy of Sciences Shanghai Astronomical Channel Structure and Dynamics Scientific Research Group used a new model of independent development- "Star-Rail Recharge Model" and high-resolution two-dimensional accumulation spectrum data, and found about 0.6 from us about 0.6 A lens galaxy of Yiguang Years had a master combination of 1380 years ago in 1380 years ago. At the same time, it revealed that the quality of the satellite galaxy that was accumulated in this time was about 40 billion solar quality. This is the oldest and most quality galaxy in the neighboring universe so far. Related results were published in August 2022 on "Astronomy Asstrophysics".

Figure 1: So far, astronomers only quantitatively portrayed the Lord and co -incident of three neighboring galaxies. Including the galaxy, it has accumulated a satellite galaxy about 10 billion years ago, with a quality of about 400 million solar quality (Helmi+2018, Belokurov+2018); After 100 million years ago, the quality of the satellite and galaxy of the satellite galaxy was about 20 billion solar quality (D'Souza +2018); and NGC 1380, which experienced a satellite galaxy about 10 billion years ago. The quality is about 40 billion solar quality. Compared with the other two galaxies, the NGC 1380 experienced the oldest and most quality coincidence.

At present, astronomers generally believe that the galaxy is formed by combined, and the galaxy has formed a large galaxy between the small galaxies. However, because most galaxies and the process of combination occur in a distant past, for astronomers, how to detect the key features of and the event of the incident from the galaxy structure we can observe today -such as the combination of co -concentration occurred together Time and accumulation satellite galaxy quality, etc. -is a challenging research topic. The ancient parallel coincidence left two clues: on the one hand, the metal abundance of the stars in the galaxy carries the information of the star and its birth environment. Then these stars' metal abundance will be relatively low; on the other hand, the stars in the galaxy follow a certain motion trajectory, and the combination leads to part of the stars on the special movement trajectory, forming the internal halo structure dominated by radial motion leaders Essence Earlier, astronomers can directly distinguish the nature of a single star in the galaxy through Wangyuan, and find this low metal abundance and have a special sports trajectory, so as to quantitatively portray the parallel experience of the galaxy. This found that the Galaxy has experienced together about 10 billion years ago, and the quality of the satellite galaxy is about 400 million solar quality [1] [2], but for most of the near neighboring galaxies, astronomers can not directly observe directly. To the nature of a single star.

The galaxy structure and dynamic group of the Shanghai Academy of Sciences Shanghai Observatory cooperated with the international team FORNAX 3D project [3] to get a high -resolution integration viewing field of the early Odarbar Acestine NGC 1380, which is 60 million light years away from the earth. Spectral data, the data on the VLT is observed by the point viewing spectrometer MUSE [4]. By analyzing this data, the researchers of the United Team obtained the distribution of sports information and chemical abundance accumulated by the galaxy in the direction of sight. In order to construct the three-dimensional running trajectory and corresponding chemical abundance in the galaxy, the galaxy structure and dynamic group have developed a new three-dimensional "Star-Rail Rehabilitation Model" [5] and apply this model to Study on the early galaxy NGC 1380. Using this model, the researchers successfully fit the observation data of all the two -dimensional plane of the galaxy.

Figure 2: Schematic diagram of NGC1380 and its inner star sports trajectory. A galaxy is composed of hundreds of millions of stars, which move these stars along a certain trajectory. By constructing the Star-Rail model, the researchers revealed the distribution of the inner star movement trajectory of the galaxy, and the age and metal abundance of the corresponding stars (the above figure is characterized by different colors). The yellow dots in the picture represent the old and low metal abundance stars. Their movement trajectory is dominated by radial motion. These stars constitute the internal dizziness structure we call, and are ancient and coincided with galaxy. The blue dots in the figure represent the younger stars. Their movement trajectory is dominated by the rotation of the cut, forming a disc structure in the galaxy.

By further analyzing the composition of the inner orbital structure of the three-dimensional star-rail model, the researchers found that the NGC 1380 has an internal halo structure composed of a star that is mainly in the trajectory of radial motion, and this internal dizziness structure is old and metal abundance Low. Researchers believe that this internal dizziness is a relic left by the ancient protagonist, which can be used to quantitatively the quality of the satellite galaxy. The quality of the NGC 1380 internal halo structure indicates that it once combined with a satellite galaxy with more than 40 billion solar quality, accounting for 1/5 of its total quality today. NGC 1380 still has a large amount of gas residues after co -connection. The stars continue to form on the disk, and the star disk formed before co -connection will inevitably be destroyed at least part of it. According to the age distribution of the stars on the trajectory of the rules rotation, the researchers speculate that the Lord of the NGC 1380 must occur about 10 billion years ago [5].

Before the work, the study of the ancient and incidents of quantitative portrayal relying on observations of a large number of single stars, so that the scope of research is limited to the two galaxies closest to the earth, namely the Galaxy [1] [2] and the fairy. In the galaxy [7]. For the first time, the research scope of the ancient parallel incident was pushed to the remote galaxy with the point spectrum data with points -see -the -spot spectrum -NGC1380, which is 60 million light years, thereby opening a new window of quantitative research galaxy and history. The star-orbital superposition model developed by the galaxy structure and dynamic group is a unique and powerful method of decomposing galaxy internal structure. "From the perspective of astronomers, in the neighboring universe, the NGC 1380 is only a flat lens galaxy. It is its flatness that it shows the general adaptability of this newly developed star-rail superposition model. . "Researcher Zhu Ling, the person in charge of the scientific research group, said," Astronomers use existing observation equipment to obtain hundreds of high-resolution integration spectrum data similar to neighboring galaxies, and the Star-Rail Model can be systematically applied systematically. To a large number of galaxies, revealing the main incidents of these galaxies have occurred, so as to study the impact of the coexistence of galaxies in the cosmic environment. "

references

[1] Helmi, A., Babusiaux, C., Koppelman, H. H., et al. 2018, nature, 563, 85

[2] Belokurov, V., ERKAL, D., ET Al. 2018, Mnras, 478, 611

[3] SARZI., Et al., 2018, aa, 616, 121

[4] Bacon, R., et al., 2010, spie, 7735, 08

[5] zhu, L., Van de Ven, G., Leaman, R., et al. 2020, mnras, 496, 1579

[6] zhu, l., pillepich., Et al., 2022A, AA, 660, 20

[7] d ’souza, R. Bell, e. F. 2018, nature Astronomy, 2, 737

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Scientific contact

Zhu Ling, Shanghai Academy of Sciences Shanghai Observatory, [email protected]

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