Astronomers report fluctuations in our giant gas neighbor. A few years ago, astronomers solved one of the Milky Way’s greatest mysteries: a vast, undulating chain of gas clouds in our Sun’s backyard that form clusters of stars along the spiral arm of the galaxy we call home.

The team named this surprising new structure the Radcliffe wave, after the Harvard Radcliffe Institute, where waviness was first discovered. Nature A Radcliffe wave not only looks like a wave, it also moves by oscillating like a wave. through space-time like a “wave” moving through a stadium full of fans.

Research by wave

Ralf Konietska, lead author of the paper and Ph.D. student at Harvard’s Kenneth Griffin Institute of Arts and Sciences, explains: “Using the motion of baby stars born in gas clouds along the Radcliffe wave, we can show that the Radcliffe wave is actually shaking by tracking the motion of their natural gas.”

In 2018, University of Vienna professor Joao Alves, while a research fellow at Harvard’s Radcliffe Institute, worked with Center for Astrophysics researcher Catherine Zucker, who was then a Ph.D. Harvard student and Robert Wheeler Wilson Professor of Applied Astronomy Alyssa Goodman teamed up to create a 3D map of the location of stellar nurseries in the Sun’s galactic region. By combining brand new data from the European Space Agency’s Gaia mission with dense 3D Dust Mapping technology pioneered by Harvard professor Doug Finkbeiner and his team, they noticed a pattern that led to Radcliffe’s discovery. Wave in 2020.

“This is the largest coherent structure that we know of, and it’s very, very close to us,” said Zucker, who described the community’s work in a related article in Sky and Telescope. “He was there from the beginning. “We didn’t know about this because we couldn’t create these high-resolution models in 3D showing the distribution of gas clouds near the Sun.”

Understanding Radcliffe Wave Motion

The 2020 3D dust map clearly showed that the Radcliffe wave existed, but at the time no measurements were good enough to see if the wave was moving. But in 2022, Alves’ group used a new version of Gaia data to assign three-dimensional motions to young star clusters in the Radcliffe wave. By looking at the positions and motions of the clusters, Konecka, Goodman, Zucker and their colleagues were able to determine that the entire Radcliffe wave was indeed oscillating, moving in what physicists call a “traveling wave.”

The running wave is the same phenomenon we see in a sports stadium, where people take turns standing and sitting to “do the wave.” Similarly, star clusters move up and down during the Radcliffe wave, creating a wandering pattern in our galaxy’s backyard.

“Just like the Earth’s gravity pulls stadium fans to their seats, the Radcliffe Wave is released due to the Milky Way’s gravity,” Konietska continued.

Understanding the behavior of this 9,000-light-year-tall giant structure in our galactic backyard, just 500 light-years away from the Sun at its closest point, now allows researchers to turn their attention to even more complex questions. No one yet knows what causes a Radcliffe wave or why it behaves the way it does.

“Now we can go and test all these different theories about what caused the wave,” Zucker said. “These theories range from the explosion of massive stars called supernovae to extragalactic disturbances such as the collision of a dwarf satellite galaxy with our Milky Way,” Konetska said. he added.

Implications and future research

Article Nature It also includes a calculation of how much dark matter can contribute to the gravity responsible for the movement of the wave.

“It turns out that a significant amount of dark matter is not needed to explain the motion we observe,” Konietska said. said. “The gravity of ordinary matter is sufficient to excite a wave.”

Additionally, the discovery of the oscillations raises new questions about the dominance of these waves in both the Milky Way and other galaxies. Since the Radcliffe wave appears to form the base of the Milky Way’s nearest spiral arm, the wave’s oscillations could mean that the spiral arms of galaxies in general are oscillating, making galaxies more dynamic than previously thought.

“The question is, what caused the change that led to the excitement we saw?” Goodman said. “And this is happening all over the galaxy? In all galaxies? Does this happen sometimes? Does this happen all the time?”