An international astronomy team has drawn a detailed three-dimensional map of the Milky Way, showing that the “body” of the Milky Way is not flat as traditionally thought, but has a curly S-shape. The research paper was published online in the American magazine Science.
The astronomical community’s previous understanding of the shape and structure of the Milky Way was mainly based on indirect measurements of celestial signatures and derivation of other distant galaxies in the universe. The shape of the Milky Way mapped from these limited observations is incomplete.
Researchers from the University of Warsaw in Poland and other institutions analyzed more than 200,000 space photos taken by the Las Campanas Observatory in Chile, and identified 2,431 Cepheids, known as the “Sky Ruler”, from 1 billion stars, and directly The distances between these Cepheids and the Sun were measured. Cepheid variables are a type of star that changes periodically in brightness and are often used to measure distances to galaxies. By determining the three-dimensional coordinates of these stars relative to the Sun, the researchers created a detailed three-dimensional map of the Milky Way.
The latest three-dimensional map shows that outward from the galactic center, the huge galactic disk will gradually roll up or down. The stars in the outer disk of the Milky Way, which is 60,000 light-years away from the galactic center, deviate from the galactic plane by as much as 4,500 light-years. The Milky Way as a whole has a curled S-shape, what astronomers describe as a warped structure.
The new research is similar to a study published in the British journal Nature Astronomy. In that paper, an international collaborative team led by the National Astronomical Observatory of the Chinese Academy of Sciences demonstrated for the first time the warped structure of the outer disk of stars in the Milky Way, with the overall S shape.
There are many explanations for the formation of the warped structure of the Milky Way. One explanation is that the interaction between the Milky Way and neighboring galaxies distorts the weakly gravitationally bound outer disk of the Milky Way, causing stars there to be pulled away from the galactic plane.
The astronomical community has previously discovered that many galaxies exhibit more or less warped shapes, and radio observations have also found that the gas disk of the Milky Way exhibits the same warped structure as many extragalactic galaxies. Researchers believe that understanding the shape of the Milky Way could help ultimately understand how giant disk galaxies like the Milky Way form and evolve.