Sneden's star, Caffau's star - all of them are galactic halo stars! What was once a title bestowed to the "Methuselah Star", we'd initially thought it was older than the Universe itself - though reestimates have finally placed its age at roughly 12 billion years. Really goes to show how far back even our own galaxy goes, huh? Most of these stars are located in the Galactic Halo - a really, really thin 'sphere' of stars surrounding the central Milky Way core, the relics of galaxy collisions long past. These collisions would've flung long, long trails of stars outwards, much like the Jellyfish Galaxy of today.