Liller 1: A Galactic Mystery, Uncovering the Origins of a Massive Star Cluster in the Milky Way’s Heart

Anna Liptrott and colleagues used APOGEE data to study whether Liller 1 helped form the Milky Way’s bulge. By comparing its chemical makeup with stars from the bulge and disk, they found that Liller 1’s α-element abundances differ significantly, showing it’s chemically distinct. The results rule out it being a major bulge “building block,” suggesting instead that Liller 1 is a minor or possibly extragalactic remnant.