NASA’s star stream data reveals how dark matter shapes galaxy orbits

The first stellar stream from a globular cluster outside the Milky Way has been identified, a discovery offering a new way to map dark matter in distant galaxies. An international team, including Northwestern University astrophysicist Tjitske Starkenburg, detected the faint ribbon of stars in the ultra-diffuse galaxy UGC 9050-Dw1, located 115 million light-years from Earth. “The stars in a stellar stream all travel along nearly the same orbit, and that orbit is…