Cloud-9 (RELHIC)

The image of the region from the advanced camera system of the Hubble space telescope, overlaid with radio emission data from the Very Large Array, which shows the extent of the cloud in magenta. The circle shows the central region searched for stars, which were not found.

CL-9's observed column density isocontours (taken from Z23)

Cloud-9 is a REionization-Limited-H i Cloud (RELHIC), and possibly a starless dark matter galaxy. ^[1] This RELHIC may have a mass 5 billion times that of the Sun and was found in the vicinity of the spiral galaxy M94, in the constellation Canes Venatici. ^[2]

First identified by the Five-hundred-meter Aperture Spherical Telescope (FAST) in 2023 and confirmed by NASA's Hubble Space Telescope in early 2026, Cloud-9 is the first confirmed example of a failed galaxy of a type predicted by the Lambda CDM cold dark matter cosmological model, having captured hydrogen gas but failed to initiate star formation. ^{[3] [4] [5] [6] [7]}

References

1. Benitez-Llambay, Alejandro; Navarro, Julio F. (September 2023), "Is a Recently Discovered H i Cloud near M94 a Starless Dark Matter Halo?", The Astrophysical Journal, 956 (1): 1, arXiv: 2309.03253 , Bibcode:2023ApJ...956....1B, doi: 10.3847/1538-4357/acf767 , ISSN   0004-637X
2. "Astronomers may have found a galaxy that's all dark matter, with no stars", Sky at Night, BBC, 2 November 2023, retrieved 2024-01-22
3. Anand, Gagandeep S.; Benítez-Llambay, Alejandro; Beaton, Rachael; Fox, Andrew J.; Navarro, Julio F.; D’Onghia, Elena (2025-11-10), "The First RELHIC? Cloud-9 is a Starless Gas Cloud", The Astrophysical Journal Letters, 993 (2): L55, arXiv: 2508.20157 , Bibcode:2025ApJ...993L..55A, doi: 10.3847/2041-8213/ae1584 , ISSN   2041-8205
4. Cloud-9: a new celestial object found by Hubble, European Space Agency, retrieved 2026-01-09
5. NASA's Hubble Examines Cloud-9, First of New Type of Object, NASA, 2026-01-05
6. [e-mail] (2026-01-07), "Scientists have found a new kind of object in deep space. And it could help solve one of the Universe's biggest mysteries", Sky at Night, BBC
7. Ahart, Jenna, "Do All Galaxies Need Stars? Astronomers Discover a New Class of Astronomical Object", Scientific American