Hubble finds faint galaxy hiding in plain sight
Astronomers using the Hubble Space Telescope have found a super-faint galaxy, CDG-2, about 245 to 300 million light-years away in the Perseus cluster.
Reported by a University of Toronto team, this tiny galaxy glows with the light of roughly 1 to 6 million Suns and has four identified globular clusters, though a few possible additional clusters were noted.
First galaxy spotted using globular clusters
Instead of spotting it by its stars, scientists identified CDG-2 by analyzing dense groups of globular clusters in Hubble's survey data—a first for astronomy.
The telescopes also picked up a faint halo around these clusters.
CDG-2 is made up of 99% dark matter
CDG-2 is made up of 99% dark matter, with almost no gas left to form new stars because it got stripped away in space.
This find shows that tracking globular clusters can help us discover more hidden galaxies with telescopes such as Euclid and the future Rubin Observatory—opening new ways to explore the universe's mysteries.