Deep images from the Hubble Space Telescope have revealed a faint stream of stars in UGC 9050-Dw1, an ultra-diffuse galaxy far beyond the Milky Way.
The feature, named Oyashio, is the first globular-cluster stellar stream identified beyond our galaxy, according to a study published in Nature.
A globular cluster is a tight group of stars. Over time, gravity can pull some of those stars away into a long, narrow stream.
By modeling the stream, the researchers measured the dark-matter halo around its host galaxy and its inner density. That gives astronomers another way to study invisible matter in distant, faint galaxies.
