[Scientific research progress] The international cooperation team led by Shanghai Observatory found the environmental characteristics of the birthplace of the star "multi -cell" -more dense and turbulent

The international cooperation team led by the Shanghai Observatory Liu Tie's international cooperation team, Almasop, used the Maxwick telescope (JCMT) led by the Astronomical Science Center of the Chinese Academy of Sciences and the ALMA large millimeter wave/Asian millimeter wave array (ALMA) in Chile. Observations were carried out, and the formation of small -quality multi -star systems was related to the physical properties of the "cloud nucleus" of the birthplace -more easily forming a multi -star system in a more dense and turbulent area. This is the first time astronomers have explored the formation of multi -star systems from the scale of the cloud nucleus. This research results laid the foundation for the theoretical theory of the formation of multi -star systems and subsequent search for the cloud that was deeply buried in the clouds and in the early formation of stars. Relevant research results were published in June 2022 in the famous Astronomical Magazine "Science Physics".

Astronomers found that they had mature "twins", "tripod twins", and even "twins" in stars in the formation area of ​​the galaxy. In previous research, due to the resolution restrictions of the telescope, astronomers generally only pay attention to the breeding process of a single "star embryo" [2] [3]. In recent years, with the improvement of the resolution of the telescope, more and more "multi -bipurbal embryos" have been identified [4] [5] -douts are in a gravity restraint system, the distance between each member embryo Waiting [6]. However, for astronomers, the origin of these double -star/multi -star systems is still unsolved.

In order to explore the environment and mechanism formed by these "twins" stars, researchers of the ALMASOP science team set their sights on the birthplace of the star- "cloud nuclear". The cloud nucleus is the cradle of the stars in the air -conditioned and dust in the molecular cloud through gravity. Each cloud nucleus has different gas density, quality, size, and the flow characteristics of internal gas. However, in previous studies, astronomers did not consider the physical properties of the "cloud nucleus" of the birthplace of the star, nor did they study how these properties affect the number of stars in the birth of the stars in the cloud nucleus.

In response, members of the Almasop group used the JCMT telescope to find 49 dense and cold cloud nuclei that are forming stars in the Orion. At the same time, the internal structure of these dense cloud cores was first revealed using Alma's high resolution. Researchers have found that in these 49 cloud nuclei, 13 cloud cores are breeding multi -star systems, and other cloud nuclei are forming single stars.

The observation data of JCMT provides researchers with the physical characteristics of these 49 cloud nuclear: their average size is about 0.1pc (20626 days distance), and the quality is only the quality of a few solars. However, when the researchers compared only the separation of the cloud nucleus that only formed a single star, it was found that the column density and number density of the hydrogen molecules of these cloud nuclei were obviously different. "We believe that the cloud core that forms a double -star/multi -star system often has a higher gas density than those cores that form a single star, and the size of the cloud nucleus does not show a significant difference." The first author of this work, the Shanghai Observatory of Shanghai Observatory, Doctoral student Luo Qiuyi said, "This phenomenon is easy to understand, and the more dense cloud nucleus will be easily broken by internal self -gravity disturbances." She also pointed out that multi -star systems are more likely to be more dense and turbulent clouds. Born in the nuclear.

The Almasop Research Group also used Wild Bianshan 45M (NRO-45M) telescope to observe the 49 cloud-core N2H+molecular spectrum lines. Observation results show that the width of N2H+molecular lines is even larger among the cloud nucleus that only form double stars/multi -stars. Professor TateMatsu, who led the NRO-45M observation project, said that the NRO-45M observation N2H+molecule reflects the turbulence level in the cloud nucleus. Essence

The co -authors of this research, Taiwan Institute of Astronomy and Astronomical Physics (ASIAA), Lu Shengyuan believes: "Observation data and analysis results in JCMT laid the cornerstone for subsequent observations and research work, and Alma provided unprecedented high high heights The sensitivity and high -resolution can let us see the original stars buried in the cloud nucleus. Therefore, we can conduct similar research on a larger dense cloud nuclear sample in order to better understand the formation of the stars. "

"We also need to consider the influence of magnetic fields in future analysis. The magnetic field may inhibit the fragmentation of the dense cloud nucleus, so we are looking forward to using JCMT and Alma in this field in the next stage." The joint communication of the project in this project. " Liu Tie, the author of the author and the head of Almasop project.

Figure: G205.46-14.56 Cloud Group is located in the Orion. High -line representatives of yellow are discovered by JCMT. The embedded map is the 1.3mm continuous spectrum radiation observed by Alma. These observations have given astronomers a deeper understanding of the formation of various star systems in the dense cloud nucleus.

references

[1] Raghavan, D., McAlister, H. A., Henry, T. J., et al. 2010, apjs, 190, 1

[2] Di Francesco, J., Johnstone, D., Kirk, H., Mackenzie, T., LEDWOSINSKA, E. 2008, APJS, 175, 277 [3] shu, F. H., ADAMS, F. C., Lizano, S. S. S. S. S. S. S. S. S. S. S. S. S. S. S. S. S. S. S. S. S. S. S. S. Lizan1987, ARAA, 25, 23

[4] Chen, X., ARCE, H. G., ZHANG, Q., et al. 2013, APJ, 768, 110

[5] Tobin, J. J., LONEY, L. W., Li, Z.-Y., ET Al. 2016, APJ, 818, 73

[6] https://arxiv.org/abs/2203.10066

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