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Model image of the Radcliffe wave in the Milky Way near the Sun (yellow dot)

Photo: Ralf Konietzka / Alyssa Goodman / WorldWide Telescope

A few years ago, astronomers discovered a huge, wave-shaped chain of gas clouds in the Milky Way that are constantly producing new stars. Although huge is probably an understatement: the structure in the vicinity of the sun stretches over a length of 9,000 light years. At its closest point it is 500 light years away.

"It's the largest connected structure we know, it's really, really close to us," says Catherine Zucker, an astrophysicist at Harvard University. “She was there the whole time. We just didn't know about it because we hadn't yet been able to create high-resolution 3D models of the distribution of gaseous clouds near the sun. Only then did they finally reveal the huge, wave-shaped gas accumulation. The researchers called it the “Radcliffe wave” after the Harvard Radcliffe Institute, where it was discovered.

In a paper in the journal Nature, the team now reports that the Radcliffe wave not only looks like a wave - but also moves like one. Similar to a La Ola wave in the stadium. Around 13 million years ago, our solar system may have even thwarted the accumulation of gas. “We surfed the wave, so to speak,” explains German Ralf Konietzka, lead author of the study and doctoral student in astrophysics at Harvard University. No damage is known.

"Using the movement of the baby stars that are born in the gas clouds along the Radcliffe wave, we were able to track the movement of the gas," said Konietzka, according to a statement. “So we were able to show that the Radcliffe wave actually moves in waves.”

Just as football fans stand up one after the other in the stadium and thereby create a wave, the star clusters also move up and down along the Radcliffe wave. “And just as fans in a stadium fall back to their seats due to the gravity of the earth, the Radcliffe wave swings due to the gravity of the Milky Way,” says Konietzka.

Structure continues to pose a mystery

The 3D map from 2020, which initially revealed the structure, already clearly showed that the wave exists. But at that point in time, no measurements were available that could have been used to determine their movement, the researchers report. Newer data collected by the European Space Agency’s “Gaia” space probe in 2022 provided a solution.

Nevertheless, the wave continues to pose a mystery - it remains unknown how it came about and why it moves like a La Ola wave. The researchers have initial theories about this, which they now want to test.