The Milky Way Boundary "finally found"
The study found that the Milky Way is about 1.9 million light-years wide

Science and Technology Daily, Beijing, March 24 (Reporter Liu Xia) According to a report by the US "Science News" website on the 23rd, a new study by British scientists indicates that the Milky Way is about 1.9 million light-years wide (1 light-year equals 946 billion km) This number helps them better estimate the mass of the Milky Way and how many galaxies "dance" with the Milky Way.

Astronomers have long known that the brightest part of the Milky Way is a pancake-like stellar disk in which the sun is located, which is about 120,000 light-years wide. Outside the stellar disk is a gas disk. A huge dark matter halo envelops the two discs and extends far beyond them. But because this dark halo does not emit light, it is difficult for scientists to measure the diameter of the Milky Way.

Now, astrophysicist Alice Dyson of Durham University and colleagues have used galaxies near the Milky Way to find the boundaries of the Milky Way. Their latest research shows that the precise diameter of the Milky Way is 1.9 million light-years, and the error is no more than 400,000 light-years.

In order to find the boundaries of the Milky Way, the Dyson team used a computer to simulate the formation of giant galaxies such as the Milky Way. They especially simulated the appearance of the Milky Way and its recent large galaxy Andromeda Galaxy side by side. The results show that the velocity of small galaxies near the edge of the dark halo of giant galaxies will decrease significantly.

Using existing telescope observations, Dyson's team found that small galaxies near the Milky Way had the same rate of decline. They said that this happened about 950,000 light years from the center of the Milky Way, which should be the boundary of the Milky Way. From this they concluded that the Milky Way is about 1.9 million light-years wide. And, although much of the Milky Way's mass is made up of dark matter, simulations show that stars may also exist on the edge of the Milky Way.

They hope to find out more nearby galaxies in the future to further pinpoint the edge of the Milky Way. Astrophysicist Mike Colchin, of the University of Texas at Austin, was not involved in the study. He said that astronomers can also look for stars on the edge of the Milky Way. Stars in these distant places may be very dim, but the future should You can find them.

Johns Hopkins University astronomer Rosemary Wise was not involved in the latest research, but she pointed out that the latest measurements could also help astronomers clarify other properties of the Milky Way. For example, the larger the Milky Way, the heavier its "weight" and the more galaxies it "dances with" it. Scientists have found about 60 "dance partners" for the Milky Way so far, and more should be found in the future.

Editor's Corner

Just like in life, distant goals are clearer, but things that are near are difficult to grasp. In Lushan, I don't know the true face of Lushan, in the Milky Way, I don't know where the river bank is. So far, we haven't fully figured out where the earth's atmosphere is? Where is the edge of the solar system? Where is the Milky Way? Perhaps clarifying this vague knowledge requires our most sophisticated instruments and the most brilliant ideas.