Student Team Finds One of the Oldest Stars in the Universe that Migrated to the Milky Way

Student Team Finds One of the Oldest Stars in the Universe that Migrated to the Milky Way By Matthew Williams - April 10, 2026 10:28 PM UTC | Extragalactic Ten undergraduate students from the University of Chicago made an astounding discovery using data from the Sloan Digital Sky Survey . As part of their "Field Course in Astrophysics," they located one of the oldest stars in the Universe living in the Milky Way. The star, SDSS J0715-7334 , is a red giant with 29 times as much mass as our Sun, located 79,256 light-years away. But here's where things truly get interesting: according to their findings, this star wasn't born in the Milky Way, but migrated here from another galaxy. The team is led by Professor Alex Ji , the deputy Project Scientist for SDSS-V, and graduate teaching assistants Hillary Andales and Pierre Thibodeaux. The SDSS-V program began in 2020 and is the latest phase of the Survey's 25-year commitment to acquiring spectra of millions of objects in the Milky Way and beyond, to improve our understanding of how stars, black holes, and galaxies grow and evolve. The program relies on two telescopes in both hemispheres to provide full-sky coverage, including the 2.5-meter Sloan Foundation Telescope at Apache Point Observatory in New Mexico and the 100-inch du Pont Telescope at Las Campanas Observatory in Chile. In Ji's class, the SDSS is embedded into the class curriculum, and the student team spent the first several weeks looking through its data for interesting stars. After examining several thousand candidates, they flagged 77 for follow-up observations using the Magellan Inamori Kyocera Echelle instrument on the Magellan telescopes at the Las Campanas Observatory. On the evening of March 21st, 2025, they found SDSS J0715-7334 and observed it for three hours. *The Large Magellanic Cloud, a satellite galaxy of the Milky Way, as imaged from the Hubble Space Telescope. Credit: NASA/JPL-Caltech* From its composition, almost entirely hydrogen/helium, they de...