New Map of Milky Way Reveals Giant Wave of Stellar Nurseries

(CN) – The universe has become an even more humbling place after a team of Harvard University astronomers discovered a galaxy-wide, wave-shaped gaseous structure that happens to form one of the closest arms of the Milky Way.

Visualization of the Radcliffe Wave, a massive, wave-shaped gaseous structure made up of stellar nurseries that is one of the largest coherent structures ever observed in our galaxy. This image, taken from the World Wide Telescope, represents the study data overlaid on an artist’s illustration of the Milky Way and our sun. (Alyssa Goodman / Harvard University)

In the scope of the universe, the giant is a next-door neighbor to Earth.

Detailing their findings in the journal Nature, astronomers delve into the Radcliffe Wave – a monolithic collection of gas about 9,000 light-years long and 400 light-years wide, with a wave-like shape that crests 500 light-years above and below the mid-plane of our galaxy’s disk.

Data from the study come from the European Space Agency’s Gaia spacecraft, which measures position, distance and motion of the stars. With additional data, researchers constructed a 3-D map of interstellar matter in the Milky Way. That’s when they noticed a pattern jutting in the spiral arm closet to Earth.

Researchers utilized data from the Gaia space telescope, numerical simulations and other sources to give them a fuller picture. Harvard graduate students Catherine Zucker and Joshua Speagle participated in compiling the data and Zucker helped put together the 3-D map used in the study.

“No astronomer expected that we live next to a giant, wave-like collection of gas – or that it forms the local arm of the Milky Way,” Alyssa Goodman, co-director of the Science Program at the Radcliffe Institute of Advanced Study, said in a statement. “We were completely shocked when we first realized how long and straight the Radcliffe Wave is, looking down on it from above in 3-D – but how sinusoidal it is when viewed from Earth. The wave’s very existence is forcing us to rethink our understanding of the Milky Way’s 3-D structure.”

Researchers say the discovery of the Radcliffe Wave shines new light on a 150-year vision of nearby stellar nurseries as an expanding ring and forces a re-evaluation of Gould’s Belt, thought to be a partial ring of stars in the Milky Way.

João Alves, professor of stellar astrophysics at the University of Vienna and a Radcliffe fellow, noted the wave’s relative proximity to our solar system.

“What we’ve observed is the largest coherent gas structure we know of in the galaxy, organized not in a ring but in a massive, undulating filament,” Alves said in a statement. “The sun lies only 500 light-years from the wave at its closest point. It’s been right in front of our eyes all the time, but we couldn’t see it until now.”

The origin of the wave is unclear. And it’s too large to have been created by a feedback of a generation of massive stars, according to the study authors.

Alves said the structure interacts with our sun and passed by a gathering of supernovae as it crossed Orion 13 million years ago. In another 13 million years it will cross again, just like a passing wave.

“More likely, this narrow structure is the outcome of a large-scale galactic process of gas accumulation, either from a shock front in a spiral arm or from gravitational settling and cooling on the plane of the Milky Way,” the study authors wrote.

The discovery of the Radcliffe Wave was a collaborative work of analysts and astronomers, who say it provides a new framework for understanding molecular cloud formation and evolution.

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