"Astronomers have just identified what appears to be a cosmic anomaly: a faint galaxy with so few visible stars that, according to calculations, as much as 99.9 percent of its mass is dark matter. The remaining 0.1 percent is conventional matter. This galaxy, located about 300 million light-years away, is practically invisible. Only four globular clusters, small concentrations of stars that look like isolated neighborhoods in the middle of the void, stand out."
"Now, after an exhaustive analysis, a study published in The Astrophysical Journal Letters presents solid evidence that these globular clusters are part of the same galaxy dominated by dark matter. Tentatively named CDG-2 (Candidate Dark Galaxy-2), it is the first galaxy to be detected only by its brightest fragments. The authors pooled data from the Hubble, Euclid, and Subaru telescopes, three of the most powerful observatories available. The combined readings reveal an extremely faint glow around the four globular clusters."
"Preliminary analysis indicates that CDG-2 has a total luminosity equivalent to about 6 million suns, with the four globular clusters contributing about 16 percent of that brightness, an unusually large share. This distribution suggests that, despite its low light, the galaxy is a gravitationally bound system, implying a particularly dense dark matter halo. Astronomers estimate that this invisible structure accounts for between 99.94 to 99.98 percent of CDG-2's total mass."
CDG-2 is a candidate dark galaxy about 300 million light-years away with extremely low stellar content and only four prominent globular clusters. Combined Hubble, Euclid, and Subaru data reveal a faint diffuse glow around those clusters, indicating an underlying galaxy too dim for individual detection. The system's total luminosity is roughly equivalent to six million suns, with the clusters contributing about 16 percent of the light. Light distribution and dynamical considerations imply a gravitationally bound system embedded in an exceptionally massive dark matter halo that constitutes about 99.94–99.98 percent of the total mass.
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