The Milky Way may have devoured another galaxy named Loki, and astronomers think they've found its remains
Space.com ·

Our home galaxy didn't pop into existence all at once. The Milky Way was formed gradually, as smaller galaxies, or dwarf galaxies, were subsumed into our own galaxy over billions of years. …
Our home galaxy didn't pop into existence all at once. The Milky Way was formed gradually, as smaller galaxies, or dwarf galaxies, were subsumed into our own galaxy over billions of years. It turns out that the stars leftover from these dwarf galaxies still share characteristics, and scientists are getting better at identifying them. By studying their similarities, scientists use these stars to determine their galaxies of origin. …
Original source: Space.com