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CDG-2: Galaxy Dominated by 99.9% Dark Matter Discovered

2/26/2026

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Summary

Story summary

CDG-2 is 99.9% dark matter, making it among the most dark-matter–dominated galaxies.
CDG-2 lies about 300 million light-years away in the Perseus galaxy cluster.
The study, led by Dayi Li of the University of Toronto, used Hubble images to analyze four densely packed globular clusters.
Early measurements suggest CDG-2 emits light equivalent to 6 million sun-like stars.
Further studies are needed to confirm these clusters' nature.

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Story summary

CDG-2 is 99.9% dark matter, making it among the most dark-matter–dominated galaxies.
CDG-2 lies about 300 million light-years away in the Perseus galaxy cluster.
The study, led by Dayi Li of the University of Toronto, used Hubble images to analyze four densely packed globular clusters.
Early measurements suggest CDG-2 emits light equivalent to 6 million sun-like stars.
Further studies are needed to confirm these clusters' nature.