I Astronomers discovered a star that went to the Milky Way with "heavy money".

In the early morning of the 30th Beijing time, the international scientific journal Nature Astronomy published an important discovery led by Japanese astronomers online: the Sino-Japanese cooperative research team led by Zhao Gang, a researcher at the National Astronomical Observatory of the Chinese Academy of Sciences, solved the mystery of a star's "life experience" for the first time by analyzing the detailed chemical characteristics of a star with an ultra-high content of heavy metal elements (including silver, europium, gold, uranium, etc.) in the Milky Way: This star originally came from a dwarf galaxy near the Milky Way.

Relying on the massive spectral data provided by LAMOST telescope, a major scientific and technological infrastructure in China, Xing and He discovered a very special star in the galactic halo. The content of heavy elements in this star greatly exceeds the average value of similar stars, and the content of magnesium is extremely low, only one-fifth of that of similar stars. This is the first time in the world that a super-rich star with low magnesium has been found in the Milky Way.

After that, the research team determined the content of 24 elements in this star by jointly observing the high-resolution spectrum of the 8-meter optical telescope with astronomers from the National Astronomical Observatory of Japan, and made a detailed comparison with dwarfs and silver halo stars.

It is found that the chemical composition of this star is obviously different from the halo star of the Milky Way, but it is highly consistent with the dwarfs around the Milky Way, indicating that this star comes from the dwarf star of the disintegration of the Milky Way, which is the exact and reliable chemical evidence of the merger of the Milky Way.

Further analysis shows that this star was formed after its original dwarf galaxy experienced an extremely rare neutron star merger event.

At this point, this seemingly ordinary star living outside the Milky Way has revealed its amazing true identity: it is an "immigrant" from a nearby dwarf galaxy and went to the Milky Way with "heavy money".

"Astronomers have been trying to find evidence that dwarf galaxies are swallowed up by the Milky Way. This work has made substantial research progress in this regard. " Xing said.

"This study provides accurate and reliable chemical evidence for the merger of the Milky Way, and provides new clues for identifying' immigrants' in the Milky Way according to the stellar spectrum." Zhao Gang said that this discovery will deepen our understanding of the formation and evolution of galaxies. (Zhao)