Ursa Major III May Be a Star Cluster, Not a Dark-Matter Dwarf Galaxy

Astronomers have long thought Ursa Major III, also called UNIONS 1, was a dark-matter-packed dwarf galaxy. But new simulations suggest it may instead be a compact star cluster bound by black holes and neutron stars. Located 30,000 light-years away, Ursa Major III contains just ~60 visible stars yet shows puzzlingly high stellar velocities. The new analysis explains th…