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The new observations highlight the variable processes that shape star systems like ours, offering a unique glimpse into the primordial stages of planetary formation.

Astronomers have captured a snapshot of a giant asteroid collision in Beta Pictoris, revealing insights into early planetary formation. The study, using data from the James Webb and Spitzer space telescopes, tracked changes in the dust around the star. The findings suggest a massive collision 20 years ago, changing our understanding of the development of this young star system.

A massive collision in the Beta Pictoris star system

Astronomers have captured what appears to be a snapshot of a massive collision of giant asteroids in Beta Pictoris, a neighboring star system known for its young age and violent planet-forming activity.

The observations highlight the changing processes that shape star systems like ours, offering a unique glimpse into the primordial stages of planetary formation.

“Beta Pictoris is at an age when planet formation in the terrestrial planet zone is still going on through collisions of giant asteroids, so what we can see here is basically how rocky planets and other bodies are forming in real time,” said Christine Chen, an astronomer at Johns Hopkins University who led the study.

The findings were presented June 10 at the 244th meeting of the American Astronomical Society in Madison, Wisconsin.

Two different space telescopes took snapshots 20 years apart of the same region around the star, called Beta Pictoris. Scientists theorize that the massive amount of dust seen in the 2004-2005 image from the Spitzer Space Telescope indicates an asteroid collision that had largely disappeared by the time the James Webb Space Telescope took its images in 2023. Credit: Roberto Molar Candanosa/Johns Hopkins University, with Beta Pictoris concept art by Lynette Cook/NASA

Significant changes in powder energy characteristics

Chen’s team noticed significant changes in the energy signatures emitted by dust grains around Beta Pictoris by comparing new data from James Webb Space Telescope with Spitzer Space Telescope observations from 2004 and 2005. With Webb’s detailed measurements, the team tracked the composition and size of dust particles in the exact region previously analyzed by Spitzer.

Focusing on the heat emitted by crystalline silicates – minerals commonly found around young stars as well as on Earth and other celestial bodies – the scientists found no trace of the particles previously observed in 2004-05. This suggests that A cataclysm between asteroids and other objects occurred about 20 years ago, pulverizing the bodies into fine dust particles smaller than pollen or powdered sugar, Chen said.

The Beta Pictoris star system

Beta Pictoris is a young star system located approximately 63 light-years from Earth in the constellation Pictoris. Known to be about 20 million years old, significantly younger than our solar system at 4.5 billion years, Beta Pictoris is of particular interest to astronomers studying planetary formation. The system contains a remarkable debris disk, indicative of ongoing planet formation, and has at least two known gas giants, Beta Pictoris b and c. The dynamical processes in Beta Pictoris, including frequent collisions and space weathering, offer valuable insight into the early stages of planetary development and the formation of terrestrial-type planets.

Evidence of cataclysm

“We think all this dust is what we saw originally in the 2004 and 2005 Spitzer data,” said Chen, who is also an astronomer at the Space Telescope Science Institute. “With Webb’s new data, the best explanation we have is that we actually witnessed the aftermath of a rare, cataclysmic event between large asteroid-sized bodies that marked a complete change in our understanding of this star system.”

The new data suggest that dust that was blown outward by radiation from the system’s central star is no longer detectable, Chen said. Initially, the dust near the star heats up and emits thermal radiation that Spitzer’s instruments detect. Now the dust, which has cooled as it moves away from the star, no longer emits these thermal characteristics.

The phenomenon of disappearing dust

When Spitzer collected the earlier data, scientists assumed that something like small grinding bodies would move and replenish the dust steadily over time. But Webb’s new observations show that the dust is gone and not replaced. The amount of dust kicked up is about 100,000 times the size of the asteroid that killed the dinosaurs, Chen said.

Beta Pictoris, located about 63 light-years from Earth, has long been a focal point for astronomers because of its proximity and random processes in which collisions, space weathering and other planet-forming factors will dictate the fate of the system.

Beta Pictoris: A young star system

At just 20 million years old—compared to our solar system’s 4.5 billion years—Beta Pictoris is at a key age when giant planets formed, but terrestrial planets may still be developing. There are at least two known gas giants, Beta Pic b and c, that also affect the surrounding dust and debris.

“The question we’re trying to contextualize is whether this whole process of terrestrial and giant planet formation is common or rare, and the more fundamental question: Are planetary systems like the Solar System that rare?” said co-author Kadin Worthen, PhD student in astrophysics at Johns Hopkins. “We’re basically trying to figure out how weird or average we are.”

Unsurpassed capabilities of the Webb Telescope

The new insights also highlight the Webb telescope’s unparalleled ability to reveal the intricacies of exoplanets and star systems, the team reports. They offer key clues about how the architectures of other solar systems resemble our own, and are likely to deepen scientists’ understanding of how early shocks affect the planets’ atmospheres, water content and other key aspects of habitability.

“Most of JWST’s discoveries come from things that the telescope has detected directly,” said co-author Cicero Lu, a former Johns Hopkins astrophysics postdoctoral fellow. “In this case, the story is a bit different because our results come from what JWST didn’t see.”

Collaborative research and funding

Other authors are Yiwei Chai and Alexis Li of Johns Hopkins; David R. Lowe, BA Sargent, GC Sloan, Julien H. Girard, Dean C. Hines, Marshall Perrin, and Laurent Pueyo of the Space Telescope Science Institute; Kerry M. Lisse of the Johns Hopkins University Applied Physics Laboratory; Dan M. Watson of the University of Rochester; Jens Kammerer of the European Southern Observatory; Isabel Rebolido of European Space Agency; and Christopher Stark of NASA Goddard Space Flight Center.

The research was supported by the National Aeronautics and Space Administration under Grant No. 80NSSC22K1752.