Seven Superclouds Sit Just Beyond The Solar System

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Astronomers have found a septet of superclouds lying just beyond the solar system. These giant strings of gas — five of which were previously unknown — sit nearly parallel to each other, and most of them undulate up and down in a wave pattern, researchers report in a paper submitted July 20 to arXiv.org.

"We finally [know] the interstellar cloud structure near us," says independent astrophysicist Bruce Elmegreen, based in Katonah, N.Y. "It's always been hard to see what is very local" to the solar system, because structures tend to blur together with most techniques.

Additionally, the superclouds, which may have formed from material shed by the Milky Way's spiral arms, house most of the local stellar nurseries and probably gave rise to them. The gaseous behemoths could help researchers trace the hierarchy of structures that lead to star formation, says Elmegreen, a pioneer of supercloud research who was not involved in the study.

The find adds to the discovery of a nearby supercloud dubbed the Radcliffe Wave reported in 2020. It comes within 1,000 light-years of the solar system, and wiggles above and below the disk of the galaxy for thousands of light-years.

Building on that work, astrophysicist Lilly Kormann of the University of Vienna and colleagues examined a 3-D map of interstellar dust within some 50 million square light-years of the sun.

The map was created using data from the Gaia spacecraft and published in 2024. Within that dust, "you see by eye some large-scale structures," Kormann says. But she didn't know exactly what they were.

The seven superclouds range in length from about 3,000 light-years to 8,000 light-years and have masses roughly 800,000 to 3.5 million times that of the sun, making them our largest neighbors.

They're probably even bigger than that, Kormann says, since the calculations were confined to the map's boundaries, and the huge strings of gas may extend beyond the edges.