"Discovery of Faint, Ancient Star System in Milky Way"
Astronomers have discovered Ursa Major III / UNIONS 1 (UMa3/U1), the faintest and lowest-mass Milky Way satellite ever detected, possibly dominated by dark matter. This ancient star system, located about 30,000 light-years from the sun, contains only about 60 stars over 10 billion years old and spans just 10 light-years across. The system was detected using data from the Ultraviolet Near Infrared Optical Northern Survey (UNIONS) and confirmed as a gravitationally-bound system using the Keck Observatory's Deep Imaging Multi-Object Spectrograph (DEIMOS). The presence or lack of dark matter in UMa3/U1 is crucial in determining whether it is a dwarf galaxy or a star cluster, potentially challenging our understanding of galaxy formation.