A group of astronomers in Poland have created the most accurate three-dimensional map of galaxies to date, showing the amazing distortion and irregularity of galaxy disks.
It is quite difficult to build such an accurate map of the Milky Way.
Because we are deep in the Milky Way, this means that we can't observe the outside of our Milky Way, which forces us to imagine its shape from the inside. High-density stars, gases and dust make our observation more complicated. Despite many restrictions, we know that the Milky Way is a spiral galaxy with a diameter of about120,000 light years, and we are about 27,000 light years away from the center of the Milky Way.
Over the years, astronomers have tried various methods to measure the Milky Way, including star counting, radio observation of gas molecules, and even extrapolating similar spiral galaxies around. The map obtained by these efforts is ok, but it is not good enough. A better way to draw the Milky Way is to directly measure the distance between us and the larger star samples scattered in the silver disk. Even better, the stars in the sample are fully studied and more accurate, which can ensure the accuracy of observation.
Using this strategy, scientists from the Observatory of Warsaw University have drawn the most accurate 3D map of the Milky Way galaxy to date. Dorota Scolon led the study, which was published in Nature Today.
Illustration: The animation shows the distorted shape of our galaxy.
Among other new discoveries, the updated 3D map shows that the S-shaped structure of the Milky Way distorts the astrolabe. Pulzemek Muroz, the co-author of this paper, described the team work in a related video, saying that the Milky Way is not as flat as pancakes, but "twisted and deformed". As we all know, the Milky Way is twisted, but new research will further explore the characteristics of these amazing twisted forms. New research shows that this distortion begins more than 25,000 light-years away from the center of the Milky Way, and it will be more difficult in the distance.
Scolon told Gizmodo, "If we can see the Milky Way from the side, we can clearly see its twisted shape. Stars 60,000 light-years away from the center of the Milky Way are as far away as 5,000 light-years above or below galactic plane, which is a large proportion. "
The reason is due to the interaction of neighboring galaxies, interstellar gas and even dark matter.
The study also shows that the thickness of the Milky Way is changing from beginning to end. As the distance from the center changes, the Milky Way will become thicker. Take our position as an example. The silver plate is about 500 light years thick, but at the outer edge, it reaches 3000 light years.
To create a 3D map, Skowron and her colleagues recorded the location of Cepheid variable stars. These young and active Supergiant star are ideal research objects, because their brightness changes regularly. In the end, the position of Cepheid variable stars in the Milky Way is more accurate than other types of stars, which is very accurate for 3D map projects.
More than 2,400 Cepheid samples have been used to create new maps, most of which can be observed by the Optical Gravitational Lens Experiment (OGLE), and the brightness of nearly 2 billion stars can be detected. The researchers observed the disk of the Milky Way galaxy for 6 years and took 206,726 photos of the sky.
Warsaw telescope is located in the Andes of Chile 1.3 meters (4.3 feet) and used for OGLE observation. It can monitor the brightness of stars for many years and measure their characteristics. This makes the map completely based on the data generated by Bighea satellite more spatial. For example, Skowron said that it is reliable only when the distance is between 1 10,000 and10.5 million light years. At the same time, the new map is more accurate than the previous map because there are more stars and "higher purity" Cepheid variable samples, she said.
Scolon told Gizmodo, "So this is the most' real' map of the Milky Way."
If this project sounds familiar, it's because the research published in Nature Astronomy earlier this year used similar techniques, and scientists from the China Academy of Sciences used different Cepheid variables on their maps, thus reaching similar conclusions. Chen Xiaodan, a scientist from the National Astronomical Observatory of Chinese Academy of Sciences, participated in the previous research. He disagreed that the new paper didn't cite the achievements of his team. Nevertheless, he still loves new science.
Chen said, "What's important is that they confirmed our early conclusions through the S-shaped astrolabe of the three-dimensional Milky Way, including the light in the outer region. The advantage of their confirmation of our achievements is that they use different data settings. Compared with our 2330 Cepheid Variables, they include 243 1, which are observed with different telescopes and passed through different filters. So far, they have reached a completely consistent result, which is gratifying. "
The new map not only shows the distortion of the Milky Way, but also finds that Cepheid variables are closely gathered in the universe and are similar in age.
Skowron said, "This clearly shows that Cepheid variables are produced in the same star-forming region of the narrow spiral arms of the Milky Way. We can see with our eyes that the formation of stars in the Milky Way is not a continuous process, but it is indeed produced in an explosion. "
The new map can also help to clarify the physical structure of the Milky Way, the number of spiral arms (still controversial), the deformation degree of spiral arms and so on. In order to improve the current map, Scolon said that observing from the northern hemisphere can increase the accuracy, and the observatory located on the other side of the galactic center made use of the dusty area adjacent to galactic plane. Infrared telescopes can play a role.
Looking ahead, Skowron hopes to record older stars so that they can see the future evolution of the Milky Way.
reference data
1.WJ encyclopedia
2. Astronomical terminology
3. George Dvozski-Grace Gizmodo
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