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Exclusive: ‘Like ripples on the sea’: Chinese astronomer tells Global Times how the Milky Way got its newly discovered ‘wrinkles’_我的网站

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    Schematic diagram of Milky Way Photo: Courtesy of Purple Mountain Observatory (PMO)
Chinese astronomers have discovered that the Milky Way is not a simple, smoothly warped disk, but contains widespread "wrinkle-like" structures resembling ripples on a water surface, providing new clues to understanding the galaxy's 3D structure and evolutionary history.
The discovery was made by a research team from the Purple Mountain Observatory (PMO) under the Chinese Academy of Sciences, using data from the "Milky Way Imaging Scroll Painting" (MWISP) survey. The findings were published online titled "Widespread corrugations superimposed on the Galactic warp in the outer CO disk" in the journal Nature Astronomy on August 7.
For decades, astronomers have known that the Milky Way's disk is not perfectly flat. Instead, its outer regions are slightly bent upward on one side and downward on the other - a structure known as a galactic warp.
However, the latest study shows that this large-scale bending is not the whole story. Smaller-scale vertical fluctuations are also embedded within the warped disk, creating a more complicated 3D structure.
"In many illustrations and in the public imagination, the Milky Way looks like a flat vinyl record," Sun Yan, associate researcher at PMO and the first author of the paper, told the Global Times on Tuesday. "In reality, the outer part of the Milky Way is more like a record that has been heated and deformed, with one side lifted and the other side lowered. That is the warp. On top of this large-scale deformation, there are additional smaller waves, which we call corrugations," Sun explained.
Using a more everyday analogy, Sun compared the Milky Way's structure to a sea surface. The warp is like a large swell that changes the overall height of the ocean, while corrugations are smaller waves superimposed on that swell.
"The two structures exist together. In our data analysis, we first removed the large-scale warp model, which allowed us to reveal the smaller wave-like patterns hidden underneath," Sun said.
The research focused on the Milky Way's outer gas disk rather than the more familiar stellar disk. According to Sun, cold molecular gas and stars provide two complementary ways to study the galaxy.
"Molecular gas is a sensitive probe for studying the vertical structure and dynamics of the galactic disk because it is concentrated near the disk plane and responds strongly to disturbances," she said.
Molecular gas is also the raw material for star formation, meaning its distribution is closely connected with the formation of young stars. The researchers traced this gas through carbon monoxide (CO) emission, which can penetrate regions obscured by interstellar dust and provide a different perspective from optical observations of stars.
The breakthrough was made possible by the MWISP survey, conducted using China's 13.7-meter millimeter-wave telescope. 
"MWISP can be understood as giving the Milky Way a large-scale medical examination using millimeter-wave observations," Sun said.
Previous CO surveys were limited in sensitivity and coverage, making it difficult to accurately study the distant outer regions of the galaxy. In contrast, the latest study identified more than 30,000 molecular cloud samples, covering about half of the Milky Way's outer disk and extending to a distance of about 26 kiloparsecs from the Galactic center.
With such a large dataset, researchers were able to first establish a model of the overall warp and then separate subtle structures from the background. The newly identified corrugations have radial wavelengths of about 3.9-7.9 kiloparsecs and vertical amplitudes of about 100-200 parsecs.
The study also identified a corrugation structure extending about 40 kiloparsecs in azimuth at a distance of around 12.7 kiloparsecs from the Galactic center. In some spiral arm regions, vertical displacements can reach approximately 200 parsecs.
The researchers believe these large-scale vertical fluctuations are likely related to "bending waves" triggered by external gravitational disturbances, suggesting that the Milky Way might have experienced more complex interactions during its evolutionary history.
Although the newly discovered structures sound dramatic, they do not have any direct impact on Earth or the solar system. "Humans cannot directly sense these corrugations," Sun said. "Their scales reach thousands or even tens of thousands of light-years, and even if these structures are evolving, such changes would not be directly perceptible on human timescales."
The study focuses on the outer disk of the Milky Way and does not include the region around the solar system. "There is currently no evidence that these structures have any observable influence on Earth's environment," Sun said.
Instead, their significance lies in what they reveal about the past. Like geological layers recording Earth's history, these galactic structures preserve traces of the Milky Way's evolutionary journey, the researchers explained.
Researchers said future studies combining more precise motion measurements and numerical simulations could further reveal the origins of these structures and their role in the long-term evolution of the Milky Way.
。    AI摘要      台行政机构拒副署法案，韩国瑜痛批违宪，卓荣泰反呛。郭正亮指韩看清对手真面目，称以后国民党内部就要好好讨论，面对这样的对手要怎么处理，并要勇于把不同意见拿出来讨论。         台当局行政机构日前宣布不副署台民意机构“三读”通过的“台湾儿少成长及未来账户条例”“有线广播电视法”部分条文修正案，使台民意机构负责人韩国瑜昨18日晚间说重话，“执政权”再大都大不过台湾地区现行宪制性规定。

B | 但台行政机构负责人卓荣泰却反呛韩，忘了读好台湾地区现行宪制性规定跟“预算法”。对此，前民代郭正亮直言，韩国瑜现在知道面对的是什么集团。

C | 他并建议，以后国民党内部就要好好讨论，面对这样的对手要怎么处理，并要勇于把不同意见拿出来讨论。         韩国瑜上周主导加速台当局今年度总预算审查，部分蓝营支持者抨击韩对台行政机构退让，且总预算通过后，卓荣泰却宣布不附署台民意机构“三读”通过的“台湾儿少成长及未来账户条例”。韩国瑜18日晚间于脸书发文痛批，台行政机构则回击，称卓荣泰正是依台湾地区现行宪制性规定所赋予的权限执行“副署权”，云云。    对于韩国瑜发文痛批台行政机构，郭正亮19日在台媒节目中表示，韩上周释出了善意，结果却换来民进党冰冷的回应，如今韩知道面对的是什么集团。但这时搬出《论语》《孟子》没有用，因为现在是在战场上，在战场上碰到流氓，“你还跟他讲《论语》”，未来的问题是“朝野”怎么互动。    郭正亮也直言，爆一爆也好，现在韩国瑜终于看清，面对的是“流氓集团”。以后国民党内部就要好好讨论，面对这样的对手要怎么处理，此外，也要勇于把不同意见拿出来讨论。

D | 每一个党都有不同意见，这没什么不对，有些问题就摊开来讲，“不同意见怎么处理？就是这样而已”。

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Published on:03:42:37