Cloud-9, a 'galaxy that wasn't,' contains no stars

Astronomers reported that Cloud-9 is a starless hydrogen cloud about 14 million light-years away and the first confirmed RELHIC, and Hubble observations indicate it is embedded in roughly 5 billion solar masses of dark matter.

Scientists announced the discovery of Cloud-9, an object that resembles a galaxy but contains no stars. It lies about 14 million light-years from Earth and was identified as the first confirmed RELHIC, a Reionization-Limited H I Cloud. The object is a cloud of hydrogen gas that astronomers believe is embedded in a much larger clump of dark matter. Researchers say Cloud-9 offers a new way to study how galaxies form and how dark matter shapes cosmic structure. Key details: - Cloud-9 was named because it was the ninth cloud found near a nearby spiral galaxy and was first reported in 2023 using China's Five-hundred-meter Aperture Spherical Telescope (FAST). - Follow-up radio observations were made with the Green Bank Telescope and the Very Large Array, which strengthened the view that the object lacks starlight. - Hubble Space Telescope observations in 2025 were used to estimate that the surrounding dark matter halo is about 5 billion times the mass of the sun and that the cloud contains roughly one million solar masses of hydrogen gas. - Only one object near Cloud-9 could plausibly be a star, and the analysis led researchers to conclude there is no substantial stellar population; the team concluded it is not a faint dwarf galaxy. - The discovery is described as the first confirmed example of a RELHIC, an object predicted by theory in which a dark matter halo accumulates gas but does not form stars. Summary: Cloud-9 gives astronomers a direct example of a starless, gas-rich structure that may be a primordial or “failed” galaxy and provides a test case for models of dark matter and galaxy formation. Researchers noted that determining how common RELHICs are across cosmic time will require more sensitive observations and planning for future telescopes.