We’ve identified the original stars that were in the Milky Way before it devoured another smaller galaxy called Gaia-Enceladus about 10 billion years ago
Source:
https://www.newscientist.com/article/2210407-the-milky-way-devoured-another-galaxy-and-weve-spotted-the-remains/?utm_campaign=RSS%7CNSNS&utm_source=NSNS&utm_medium=RSS&utm_content=home