Ying found a "fossil galaxy" deep in the Milky Way
Science and Technology Daily (Reporter Liu Xia) British scientists wrote in the recent "Monthly of the Royal Astronomical Society" that they used data provided by the Sloan Digital Sky Survey (SDSS) Galaxy Evolution Experiment (APOGEE) to find a hidden in the Milky Way The "fossil galaxy" in the depths.
This discovery may refresh our understanding of the evolutionary history of the Milky Way.
Researchers named this "fossil galaxy" "Hercules", thinking that it might have collided with the Milky Way, which was still in its infancy, 10 billion years ago.
Research team member Ricardo Skiavin of Liverpool John Moores University explained: “To find such a fossil galaxy, we must study the detailed chemical composition and motion of thousands of stars. This pair is located in the center of the Milky Way. It is especially difficult for stars because they are obscured by interstellar dust clouds. APOGEE allows us to penetrate the dust and see deeper in the center of the Milky Way. "To do this, APOGEE needs to use near-infrared light instead of visible light to photograph stars.
During the 10-year observation period, it mapped the spectra of more than 500,000 stars in the Milky Way, including those in the center of the Milky Way that were previously obscured by dust.
The lead author of the study and APOGEE graduate student Danny Horta explained that in order to distinguish stars belonging to "Hercules" from stars belonging to the original galaxy, the research team used the APOGEE instrument to measure the chemical composition and speed of the stars, and found that there were several hundred The chemical composition and speed of a star are very different from others.
"They are so different. They can only come from another galaxy. By studying them in detail, we traced back the precise location and history of this fossil galaxy."
Studies have shown that the "remains" of "Hercules" account for about one-third of the spherical halo of the Milky Way, which means that this collision event is a major event in the history of the Milky Way. It also indicates that the Milky Way may be very unique because of its large Most massive spiral galaxies similar to the Milky Way are calmer in their infancy.
According to the researchers, APOGEE is the flagship project of the fourth phase of SDSS (now ended). The fifth phase of SDSS has begun to collect data. Its "Galaxy Plotter" will use near-infrared light and visible light to draw The spectra of more stars further reveal the secrets of the Milky Way.