A multinational team of astronomers from the University of Groningen in the Netherlands and the University of La Laguna in Spain has identified a vast intergalactic river of stars, named the Giant Coma Stream. The finding appears in Astronomy and Astrophysics (A&A). The team emphasizes that this structure represents the largest of its kind observed so far and marks the first instance of a stellar flow connecting different galaxies. The Giant Coma Stream stretches across a distance equivalent to about ten times the diameter of the Milky Way.
The object’s name ties to the Coma Cluster, one of the most thoroughly studied galactic ensembles. This cluster houses thousands of galaxies and lies roughly 300 million light-years from Earth in the constellation Coma Berenices. The discovery of the Giant Coma Stream stands out because it reveals a delicate, fragile feature existing amid the dynamic and harsh environment where galaxies attract and repel one another. Researchers stress the importance of this finding for understanding how stars can migrate across intergalactic space and how large gravitational forces shape such flows.
Looking ahead, astronomers plan to employ large telescopes and extended observation campaigns to examine the stream in greater depth. The goal is to map its structure with higher precision, determine the forces maintaining it, and identify potential similar stellar rivers hidden in the cosmic web. The work also sets the stage for a broader search for other intergalactic stellar streams that can illuminate the history of galaxy interactions and mergers on cosmic scales.
Earlier observations revealed Stars in the Magellanic Stream, a gas-rich belt that lies between the Milky Way and neighboring galaxies. This earlier discovery helps contextualize the current finding, highlighting the growing evidence that vast streams can form and persist in the space between galaxies, tracing past gravitational encounters and ongoing dynamics. In both cases, astronomers see a tangible record of how galaxies exchange material and influence each other’s evolution over millions to billions of years. [Citation: Astronomy and Astrophysics, 202x]