NASA's Hubble Telescope Discovers First Starless Gas Cloud 'Cloud-9' Dominated By Dark Matter

Astronomers working with NASA’s Hubble Space Telescope have identified an unusual cosmic structure that contains no stars but is rich in gas and dominated by dark matter. 

The object, nicknamed “Cloud-9”, is believed to be a leftover from the universe’s earliest period of galaxy building. Researchers say it marks the first verified example of its kind, offering fresh clues about how galaxies took shape and how dark matter behaves.

“A team using  NASA Hubble Space Telescope has made the first confirmed detection of a new type of astronomical object: a starless, gas-rich, dark-matter cloud, nicknamed Cloud-9,” NASA said on its official X handle.

“This is a tale of a failed galaxy,” said the team’s principal investigator, Alejandro Benitez-Llambay of the Milano-Bicocca University in Milan, Italy. “In science, we usually learn more from the failures than from the successes. In this case, seeing no stars is what proves the theory right. It tells us that we have found in the local universe a primordial building block of a galaxy that hasn't formed.”

Published in The Astrophysical Journal Letters, the findings were introduced at a press briefing held as part of the American Astronomical Society’s 247th meeting in Phoenix, Arizona.

The structure has been identified as a Reionisation-Limited H I Cloud, or RELHIC, a term used to describe a primordial cloud of neutral hydrogen dating back to the universe’s earliest era. The “H I” label refers to neutral hydrogen, while the classification itself reflects a cloud that never progressed to forming stars.

Although scientists have long predicted the existence of these elusive objects, confirmation only came after Hubble observations showed the cloud to be completely star-free.

“This cloud is a window into the dark universe,” said team member Andrew Fox of the Association of Universities for Research in Astronomy/Space Telescope Science Institute (AURA/STScI) for the European Space Agency.

“We know from theory that most of the mass in the universe is expected to be dark matter, but it’s difficult to detect this dark material because it doesn’t emit light. Cloud-9 gives us a rare look at a dark-matter-dominated cloud.”

Researchers believe RELHICs are concentrations of dark matter that never gathered sufficient gas to trigger star formation. As a result, they offer a rare glimpse into the earliest phases of galaxy creation. 

The identification of Cloud-9 points to the likely presence of numerous other small, dark matter-heavy structures: essentially galaxies that never fully formed. Scientists say such objects could help shed light on the universe’s hidden components, which are usually obscured by studies centred on luminous stars and galaxies.

The name Cloud-9 reflects the order in which the object was identified, as it was the ninth gas cloud detected near the edge of the spiral galaxy Messier 94 (M94). Located in close proximity to M94, the cloud appears to be physically linked to the galaxy. Detailed radio observations have revealed subtle irregularities in the gas, suggesting possible interaction between the two.