Astronomers have discovered that many of the star-forming regions we see in the sky actually seem to form an undulating, 8, – – light-year-long wave containing 3 million solar masses’ worth of gas that could make up our local arm of the Milky Way galaxy.
Astronomers have long thought that a large, expanding ring of young stars, gas, and dust surrounded our solar system, forming a region called “Gould’s Belt.” But when a team of scientists in the United States, Austria, and the United Kingdom actually measured the distances to the supposedlyly comprising this belt, they found that the belt did not exist — and instead, these objects formed a far stranger structure. They’re calling it the Radcliffe Wave.
“We think we’ve found the largest coherent star- forming structure [yet observed], and it’s right under our noses, ”Catherine Zucker, graduate student at the Harvard Smithsonian Center for Astrophysics, told Gizmodo.
Back in April, the European Space Agency released the second batch of data from the Gaia spacecraft, including the positions of 1.7 billion stars and the motions of 1.3 billion. That fall, University of Vienna astrophysicist João Alves began a fellowship at the Radcliffe Institute for Advanced Study at Harvard University. Alves hoped to use the trove of Gaia data in order to create a map of the young stars, gas, and dust in the local interstellar neighborhood. He collaborated with Zucker and the other study authors, who had developed a simpler method to measure the distances to nearby dust clouds. The method combines the Gaia light plus the distances and colors of distant stars to see how their light has been scattered by intervening dust clouds — the very dust clouds they were interested in mapping.
As the scientists performed the analysis, they slowly realized that many of the famous nebulas and gas clouds in the sky, such as the Orion Nebula, did not form a ring as they expected. Instead, these dust clouds aligned, ultimately into a 8, 823 -light-year-long stripe with a wave in it as if it had been been plucked like a string, according tothe paperpublished today in Nature. Not entirely convinced, the researchers organized a red team meeting, calling on their colleagues to try to debunk the results, said Zucker. But the results held up, no matter how they tried to poke holes in them.
Given the size and shape of the structure, the team had reason to believe that they’d just pieced together a part of the local arm of our spiral-shaped Milky Way galaxy.
“Beautiful spirals [in other galaxies] are made of segments,” Alves told Gizmodo. He suspected his team had found such a segment. “We’re so close to it that we didn’t recognize it before.” The structure doesn’t quite align with past measurements of the galactic arm, however. You can look at an interactive 3D map of the Radcliffe Wave structure, the location where Gould’s Belt would have been, and the arm of the galaxyhere.the structure of the local galaxy at Smithsonian Astrophysical Observatory, told Gizmodo in an email. But Reid said the measurement of the structure “checks out well against highly accurate distances using radio astronomy techniques.”
“The relationship of structures like the Radcliffe Wave to the formation of larger spiral arms in the Milky Way remains Uncertainty, but certainly intriguing, ”Mark Reid, a senior radio astronomer not involved in this workwho studies
) Now that researchers have found such a structure, they want to figure out how it was created and what in the universe could have produced a giant waveform that causes gas to bulge light-years out of the galactic plane in either direction. That’s still a mystery — some sort of massive object, like a dwarf galaxy, must have perturbed all of the gas, Alves said, but he couldn’t think of any candidates that would have passed by and caused the wave. Perhaps the culprit is dark matter, the mysterious mass that appears to form the universe’s scaffolding and much of the mass in galaxies. The researchers hope to run computer simulations to see if they can recreate the structure and potentially find similar structures in other galaxies.