A team of astronomers and astrophysicists at the Chinese Academy of Sciences and the University of Toronto has found what they believe is the oldest stellar disk in the Milky Way galaxy. In their study, reported in the journal Nature Astronomy, the group used high-α stars with substantial orbital angular momentum to conduct age determinations across a wide range of stars in the galaxy.

Prior research has shown that the Milky Way started its life as a single entity. Over time, it has drawn in multiple other galaxies, making it much bigger—remnants of such galaxies have been found throughout the Milky Way. Such additions have made it difficult for astronomers to determine the original structure of the Milky Way.

In this new effort, the research team claims that by dating a large number of stars in different parts of the galaxy, they were able to narrow their focus to a particular group that they believe represents the original galaxy disk. The team named the disk PanGu.

Source:

The formation and survival of the Milky Way’s oldest stellar disk

https://www.nature.com/articles/s41550-024-02382-w