Astronomers used NASA’s James Webb Space Telescope to image hot dust around the nearby young star Fomalhaut to study the first asteroid belt ever seen outside our solar system in infrared light. But they were surprised that their dust structures are much more complex than our solar system’s asteroids and Kuiper dust belts. In total, there are three interlocking belts extending 14 billion miles (23 billion kilometers) from the star; It is 150 times greater than the Earth’s distance from the Sun. The outer belt is about twice the scale of our Solar System’s Kuiper belt, which consists of small bodies and cold dust beyond Neptune. Never-before-seen inner belts were first discovered by Webb.

The belts surround a young, hot star visible to the naked eye as the brightest star in the southern constellation Pisces. Dust belts are debris from collisions of larger objects, such as asteroids and comets, and are often described as “disks of debris.” “I can describe Fomalhaut as an archetype of debris disk found elsewhere in our galaxy because it contains components similar to those we have in our planetary system,” said András Gaspar of the University of Arizona in Tucson and lead author of the new paper. . explains these results. “By looking at the patterns in these rings, if we can get images deep enough to see the suspected planets, we can start to get a little sketch of what a planetary system might look like.”

The Hubble Space Telescope and the Herschel Space Observatory and the Atacama Large Millimeter/submillimeter Array (ALMA) have previously captured clear images of the outer belt. But none of them found any internal structure. Inner belts were first detected by Webb in infrared light. “What Webb really excels at is that we can physically separate the thermal dust glow in these interior regions. “So you can see interior belts that we’ve never seen before,” said Schuyler Wolff, another team member at the University of Arizona.

Hubble, ALMA, and Webb team up to create a complete picture of the debris disks around several stars. “With Hubble and ALMA, we were able to image most of their Kuiper belt counterparts and learned a lot about how outer disks form and evolve,” Wolff said. “But Webb should allow us to photograph a dozen asteroid belts elsewhere. We can learn as much about the warm inner regions of these disks as Hubble and ALMA have taught us about the colder outer regions.”

These belts were most likely carved by the gravitational forces created by unseen planets. Similarly, in our solar system, Jupiter occupies the asteroid belt, the inner edge of the Kuiper belt is chipped by Neptune, and the outer edge may be grazed by yet-to-be-seen objects beyond. As Webb captures more systems, we’ll learn about the configurations of his planets.

Fomalhaut’s dust ring was discovered in 1983 during observations by NASA’s Infrared Astronomy Satellite (IRAS). The ring’s presence has also been inferred from earlier long wavelength observations of Mauna Kea, Hawaii, by submillimeter telescopes at NASA’s Spitzer Space Telescope and the Caltech Submillimeter Observatory.

“The generations around Fomalhaut are a kind of mystery novel: where are the planets?” Another member of the team and US scientist at the Webb Infrared Instrument (MIRI) who made the observations said George Riecke. “To say that there is probably a really interesting planetary system around a star is not a big step.”

“We didn’t expect a more complex structure with a second middle belt followed by a wider asteroid belt,” Wolff added. “This structure is very exciting because whenever an astronomer sees a gap and a ring in a disk, ‘There may be a buried, ring-forming planet there!’ they say.

Webb also imaged what Gaspar called the “big dust cloud”; this could be evidence of a collision occurring in the outer ring between two protoplanetary bodies. This is different from the planet Hubble supposedly saw inside the outer ring in 2008. Other Hubble observations showed that the object had disappeared by 2014. A plausible interpretation is that this newly discovered feature, like the previous one, is a cloud of very fine dust particles expanding from two icy bodies colliding.

The idea of ​​a protoplanetary disk around a star dates back to the late 1700s, when astronomers Immanuel Kant and Pierre-Simon Laplace independently theorized that the Sun and planets formed from a rotating cloud of gas that collapsed and flattened under the influence of gravity. . The debris disks then develop after the formation of planets and the dispersal of primordial gas in the systems. They show that small objects such as asteroids collide disastrously and split their surfaces into large clouds of dust and other debris. Observations of their dust provide unique clues about the structure of an exoplanet system that reaches Earth-sized planets and even asteroids too small to be seen individually.