The largest “river” of stars ever observed has been discovered: ten times longer than the Milky Way, and the only river known so far to run in intergalactic space. Called the Coma Giant Stream, it is located in the Coma Cluster, a group of galaxies located about 350 million light-years away in the direction of the Coma Berenice constellation.
This discovery has been published, which may provide new ideas for the study of dark matter in the Journal of Astronomy and Astrophysics by an international group led by Javier Roman, working between the University of Groningen (Netherlands) and the University of La Laguna in Tenerife (Spain).
The researchers found the river of stars by chance while studying star halos around large galaxies. The first observations were made using astronomer Michael Rich’s 70-cm telescope in California. Next, the 4.2-meter William Herschel telescope located in La Palma was used. Once the images were processed, the researchers were able to detect a very faint stream of stars, which appeared to be floating in the middle of the cluster, and not associated with any particular galaxy.
This discovery is important because it is not easy to find such fragile structures in hostile environments, where galaxies attract and repel each other. Researchers have also simulated similar streams of stars with a computer, and expect to find more, thanks to the Future Very Large Telescope in Chile and the Euclid Space Telescope. Using these telescopes, they also intend to further study the giant Coma Stream itself, observing individual stars in and near the stream and learning more about the dark matter it contains.
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