• NASAâ s Hubble spots nearly invisible â ghost galaxyâ made of 99% dark matter A nearly invisible â ghost galaxyâ made of 99% dark matter has been uncovered using star clusters as cosmic clues. • Most galaxies blaze with billions of stars, lighting up the universe across vast distances. • But a small and unusual group barely glows at all. • These are low-surface-brightness galaxies, systems so faint they are difficult to detect and so sparse in stars that dark matter makes up most of their mass. • One of these hidden objects, known as CDG-2, could rank among the most dark matter dominated galaxies ever identified. • (Dark matter is an invisible form of matter that does not reflect, emit, or absorb light.) The discovery was reported inThe Astrophysical Journal Letters.
Article Summaries:
- NASA’s Hubble Space Telescope, together with ESA’s Euclid and the Subaru Telescope, has identified a faint “ghost galaxy” named CDG‑2 in the Perseus cluster, about 300 million light‑years away. The galaxy is almost invisible in starlight, yet it contains four tightly packed globular clusters that served as markers for its detection. Follow‑up imaging revealed a diffuse halo of light, confirming the presence of a galaxy whose mass is dominated by dark matter-estimated at roughly 99 % of its total mass. CDG‑2 may rank among the most dark‑matter‑rich galaxies known, illustrating how globular clusters can uncover otherwise hidden structures.
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