Student Posters Repository

The stars currently present in the outskirts of the Milky Way (called the “stellar halo”) preserve a record of the Galaxy’s formation history. Galaxies form primarily through mergers, by absorbing smaller galaxies to grow larger. While most of the stars in the center and disk of a galaxy are formed in situ, the stars in the stellar halo primarily originated from the many small galaxies that the central host galaxy accreted over billions of years. Currently, though, we lack ways to identify which halo stars originated in which dwarf galaxies or even reliably identify which stars were accreted. Selecting stars with specific chemical signatures may provide a way forward. Using high-resolution cosmological simulations, we find that r-II halo stars may have chiefly originated in early dwarf galaxies that merged to form the Milky Way. The r-II stars we observe today could thus play a key role in understanding the smallest building blocks of the Milky Way. This work is a first step towards creating a detailed theoretical model of stellar halo evolution. With such a model, we will be able to interpret forthcoming stellar halo data obtain a deep understanding of how our galaxy, and the galaxies around us, formed.