A few years ago, astronomers uncovered one of the Milky Way’s greatest mysteries: a giant, wave-shaped series of gas clouds behind our Sun, which have formed clusters of stars along the galaxy’s spiral arms. Gave birth to what we call home.

Naming this astonishing new structure Radcliffe waveIn honor of Harvard Radcliffe Institutewhere the undulation was originally discovered, the team now reports. The nature That the Radcliffe wave not only looks like a wave, but also moves like one – moving through spacetime as “the wave” moves through a stadium full of fans.

Ralph Konitzka, lead author of the paper and Ph.D. student at Harvard’s Kenneth C. Griffin Graduate School of Arts and Sciences, “By using Radcliffe waves as well as the motion of baby stars born in gaseous clouds, we can trace the motion of their birth gas so that To show that Radcliffe is a wave. Actually waving.”

Back in 2018, when a professor at the University of Vienna Play Elvis Harvard was a fellow at the Radcliffe Institute, working with him. Center for Astrophysics researcher Catherine Zucker – then a PhD student at Harvard – and Alyssa Goodman, Robert Wheeler Wilson Professor of Applied Astronomy, to map the 3D positions of stellar nurseries in the Sun’s galactic neighborhood. By combining brand-new data from the European Space Agency’s Gaia mission with data-driven “3D dust mapping” techniques – the launch Harvard professor Doug Finkbanner And his team – they saw a pattern emerge, which led to Radcliffe wave discovery in 2020.

“It’s the largest integrated structure that we know of, and it’s really, really close to us,” said Zucker, describing the collaboration’s work in a related. The sky and the telescope Article “It’s been there all along. We just didn’t know about it, because we couldn’t make high-resolution models of the distribution of gaseous clouds near the Sun in 3D.

The 2020 3D dust map clearly showed that the Radcliffe wave was present, but no measurements were available at the time that were good enough to see if the wave was moving. But in 2022, using a new release of Gaia data, Alves’ group assigned 3D motions to clusters of young stars in the Radcliffe Wave. By tracking the positions and motions of the clusters, Konitzka, Goodman, Zucker, and their colleagues were able to determine that the entire Radcliffe wave was indeed undulating, moving in what physicists call a “traveling wave.” say

A traveling wave is the phenomenon we see in sports stadiums when people stand and sit in order to “wave.” Similarly, star clusters move up and down with a Radcliffe wave, creating a pattern that sweeps through our galaxy’s background.

“Just as fans in a stadium are pulled back into their seats by Earth’s gravity, the Radcliffe wave oscillates by the gravity of the Milky Way,” Konitzka continued.

Understanding the behavior of this 9,000-light-year-long, massive structure in our galaxy’s background, which is only 500 light-years from the Sun at its closest point, allowed researchers to turn their attention to more difficult questions. Gives. No one yet knows what causes the Radcliffe wave or why it moves.

“Now we can go and test all these different theories as to why the wave formed in the first place,” Zucker said.

“Those theories range from massive stellar explosions, called supernovae, to extragalactic disturbances, such as dwarf satellite galaxies colliding with our Milky Way,” Konitzka added.

The Nature article also includes a calculation of how much dark matter is contributing to the gravity responsible for the wave motion.

“It turns out that no significant dark matter is needed to explain the motion we observe,” Konitzka said. “Only the gravity of ordinary matter is sufficient to drive a wave.”

In addition, the discovery of oscillations raises new questions about the predominance of these waves in both the Milky Way and other galaxies. Because the Radcliffe wave appears to form the backbone of the nearest spiral arm in the Milky Way, the wave ripples may mean that the spiral arms of galaxies oscillate normally, making galaxies more dynamic than previously thought. They make

“The question is, what are the waves we see due to displacement?” Goodman said. “And does it happen throughout the galaxy? All galaxies? Does it happen occasionally? Does it happen all the time?”

This work was supported by the National Science Foundation, NASA, ESA, and the European Research Council (ERC) Advanced Grant ISM-FLOW.