A team of astronomers led by the University of Victoria and Yale University has detected an ancient star system traveling around our galaxy called Ursa Major III / UNIONS 1 (UMa3/U1)

The faintest and lowest-mass Milky Way satellite ever discovered, and possibly one of the most dark matter-dominated systems known.

Is UMa3/U1 a galaxy or a star cluster? The main question astronomers have is this: is UMa3/U1 a true dwarf galaxy or is it a star cluster? The answer may come down to a mysterious and invisible substance – dark matter.

Galaxies are thought to be held together by the gravitational pull of dark matter – a type of matter we can't see directly, but which scientists know exists due to its gravitational effects.

On the other hand, gravity alone usually binds stars together into star clusters, often without the help of dark matter.

However, the surprising spread of UMa3/U1 stars did not lead to their disintegration by the gravitational forces of the Milky Way. Could dark matter be the invisible glue that holds this cosmic relic together?

“The object is so insignificant that its long-term survival is very surprising,” explains Will Cerny, a Yale University graduate student involved in the study. “We might expect that the strong tidal forces of the Milky Way's disk would have already destroyed the system, leaving no observable trace.”

UMa3/U1 as a galaxy First, UMa3/U1 may be a true dwarf galaxy, an entity with an incredibly low amount of visible matter compared to what we typically observe in these galaxies.

This feature makes it an intriguing subject of study, as it suggests that UMa3/U1 could be predominantly composed of dark matter.

If UMa3/U1 is indeed a dwarf galaxy rich in dark matter, it could provide valuable information about the role of dark matter in the formation and evolution of galaxies.

It could support the theory that many of these dark matter-dominated galaxies exist but remain hidden from our view, potentially revolutionizing our understanding of the structure of the Universe.