Every second, more than 3,000 stars are born across the universe, and many of these stars are surrounded by what astronomers call protoplanetary disks—swirling clouds of gas and dust where planets eventually form.
Despite the importance of these disks, the exact process by which stars and planetary systems form has remained somewhat of a mystery.
Now, using NASA’s James Webb Space Telescope, a team of astronomers led by the University of Arizona has made a big breakthrough.
They’ve observed powerful winds of gas blowing from these planet-forming disks, revealing how these winds shape young planetary systems. The study gives us a glimpse of what our own solar system may have looked like 4.6 billion years ago.
The team was particularly excited to trace “disk winds” in more detail than ever before.
These winds, driven mainly by magnetic fields, blow gas away from the disk into space, reaching incredible speeds—traveling tens of miles per second!
The findings, published in Nature Astronomy, help scientists better understand how young planetary systems form and evolve.
According to lead author Ilaria Pascucci, a professor at the University of Arizona’s Lunar and Planetary Laboratory, one of the key processes in these disks is the way young stars “eat” the gas from the surrounding disk.
This process, known as accretion, helps stars grow bigger. But for this to happen, the gas must first lose some of its “spin” or angular momentum. Otherwise, it would just keep swirling around the star instead of falling onto it.
Understanding how gas loses angular momentum has been challenging for scientists. To explain it, imagine a figure skater spinning on the ice.
When she pulls her arms in, she spins faster, and when she stretches her arms out, she slows down. Although her speed changes, her angular momentum stays the same.
For stars to grow by pulling in gas, that gas must lose angular momentum—similar to the skater slowing down. But how this happens has been hard to pin down.
In recent years, scientists have suggested that disk winds play a big role in this process. These winds blow away some of the gas and, with it, the angular momentum, allowing the remaining gas to fall toward the star.
The James Webb Space Telescope allowed the team to study different types of disk winds. For example, they observed magnetic winds, thermal winds (caused by the star’s heat), and a type called the X-wind.
By tuning the telescope’s sensors to detect specific molecules, they were able to see different layers of the winds, revealing a complex, onion-like structure.
The research team focused on four protoplanetary disks, all of which appear “edge-on” from Earth. This unique angle allowed the dust and gas in the disks to block out some of the bright star’s light, making it easier to observe the winds.
They discovered that these winds come from a broad region of the disk, one that could include the area where rocky planets like Earth and Mars might form.
One fascinating finding was that all four disks showed a consistent central hole inside the wind structure, created by the molecular winds.
Next, the researchers plan to study more protoplanetary disks to see how common these wind structures are and how they evolve over time. “We think these winds could be very common,” Pascucci said. “But with only four disks, it’s hard to say for sure. We want to observe more and see how they change as stars grow and planets form.”
This new understanding of protoplanetary disks could help unlock more secrets of how stars and planets, like those in our solar system, are born.
Source: University of Arizona.
This artist’s impression of a planet
