This new study by scientists at Ohio State University provides the latest evidence for the formation of the Milky Way, including the merger with a major satellite galaxy. The research was published in the journal Natural Astronomy and was conducted using a relatively new method.
Using these and other data, researchers were able to show what happened when the Milky Way merged with an orbiting satellite galaxy called Gaia Enceladus about 10 billion years ago. There is evidence that the Milky Way has formed a large number of its own stars after the merger. Many of these “master” stars are trapped in a thick disk at the center of the Milky Way, and most of the stars captured by Gaia Enceladus are located in the outer halo of the Milky Way.
By calculating the age of the stars, researchers were able to determine for the first time that the stars captured by Gaia Enceladus are similar or slightly smaller than most stars in the Milky Way. Vincenzo said that the violent merger of the two galaxies has messed things up. It turns out that this merger changed the orbits of the stars that already existed in the galaxy, making them more eccentric.
Vincenzo compares the movement of stars to a dance in which the movement of stars in ancient Gaia-Enceladus is different from the movement of stars in the Milky Way. According to Vincenzo, the “dress” of stars is even different: the chemical composition of outer stars is different from that of stars in the Milky Way. Researchers use different methods and data sources for research.
One way researchers can achieve such accurate star age is to use astronomy, a relatively new field for studying the internal structure of stars. Mathieu Vrard, a researcher at the Ohio Astronomical Bureau, said that they are propagated in stars, and they are sound waves propagating inside them. The study also used a spectroscopic study called APOGEE, which provided the chemical composition of stars to further help determine the age of stars.