Intriguingly, this river of stars could be held together by a long-dead galaxy's lingering dark matter.
Scientists say they've discovered a vast trail of about 200 stars is streaming towards the center of the Milky Way — a starry river they think could be the remains of an ancient dwarf galaxy devoured by our own.
"I was not expecting to see new stellar streams, but it was a great surprise," Lina Necib, a Postdoctoral Fellow at the California Institute of Technology, told Newsweek.
The galactic merger hypothesis seems to be the most likely origin story for the stars, according to research published Monday in the journal Nature Astronomy based on a new analysis of data from the European Space Agency's Gaia spacecraft. Necib dubbed the stellar stream "Nyx," after the Greek goddess of the night, and the mother of death and darkness.
"Using the next Gaia data release," Necib added, "we will also look at the extension of the Nyx stars further from the plane of the Milky Way and build a coherent story of the formation of the Milky Way."
If the stars really came from some ancient dwarf galaxy, then it's also possible the stellar stream is held together by some of that galaxy's dark matter — giving astronomers an interesting new place to look for it. But there's no guarantee that's the case, Newsweek reports. The stars could also, Necib admits, be Milky Way natives that simply got jostled out of place.
"It could also be stars from the disk of the Milky Way that are vibrating because of a collision of the disk," Necib told Newsweek.
READ MORE: Vast Stream of Stars From Beyond Milky Way Found Moving Toward Galaxy Center [Newsweek]
More on the galaxy: This Star Drifted Into the Milky Way From Another Galaxy