Astronomers have discovered a faint stellar stream around a galaxy 115 million light-years away—the first globular cluster star stream ever identified outside the Milky Way. Published in Nature, the Northwestern University study shows how this delicate ribbon of stars could help map the universe’s most elusive substance: dark matter.
- What It Is: As dense star clusters orbit a galaxy, gravity strips away stars into a thin arc along the same path. Found around UGC 9050-Dw1, a star-sparse galaxy, the stream stood out clearly against the unusually dark backdrop in Hubble archival data.
- Mapping Dark Matter: Because dark matter makes up ~85% of cosmic matter but remains invisible, scientists traced it through gravity. By simulating the stream's shape, researchers confirmed it can accurately estimate a distant galaxy's mass and dark matter distribution.
Future Possibilities
Small concentrations of dark matter may disturb these delicate streams, potentially creating visible gaps or clumps. If confirmed, this could give astronomers a new way to test how dark matter behaves. Upcoming missions like NASA's Nancy Grace Roman Space Telescope could make these faint structures much easier to spot across the cosmos.
Source: Science Daily
