Astronomers have observed a giant asteroid collision in Beta Pictoris using data from the Webb and Spitzer telescopes. The event, which took place 20 years ago, provides new insights into early planetary formation in this young galaxy. (Artist’s concept.) Credit: NASA
New observations illuminate the volatile processes that shape star systems like ours, offering a unique glimpse into the initial 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 dust changes around the star. The findings point to a massive collision twenty years ago that changed our understanding of the development of this young galaxy.
Massive collision in the beta Pictoris galaxy
Astronomers have captured what appears to be a snapshot of a massive collision of giant asteroids in Beta Pictoris, a neighboring galaxy known for its young age and tumultuous planet-forming activity.
The observations illuminate the volatile processes that form galaxies like ours, providing a unique glimpse into the initial stages of planetary formation.
“Beta Pictoris is at an age where planet formation in the terrestrial planet zone is still ongoing through collisions with giant asteroids, so what we could be seeing here is essentially how rocky planets and other bodies are forming in real time,” says Christine Chen, one of the researchers. Johns Hopkins University astronomer who led the study.
The insights were presented June 10 at the 244th meeting of the American Astronomical Society in Madison, Wisconsin.
Two different space telescopes took pictures of the same area around the star Beta Pictoris twenty years apart. Scientists theorize that the massive amount of dust seen in the 2004-2005 Spitzer Space Telescope image indicates a collision of asteroids that had largely disappeared by the time the James Webb Space Telescope captured its images in 2023. Credit: Roberto Molar Candanosa/Johns Hopkins University, with Beta Pictoris concept art by Lynette Cook/NASA
Significant changes in dust energy signatures
Chen’s team has noticed significant changes in the energy signatures emitted by dust grains around Beta Pictoris through new data from the James Webb Space Telescope with observations from the Spitzer Space Telescope from 2004 and 2005. Using Webb’s detailed measurements, the team tracked the composition and size of the dust grains in the exact area previously analyzed by Spitzer.
By focusing on the heat emitted by crystalline silicates – minerals often found around young stars, as well as on Earth and other celestial bodies – the scientists found no traces of the particles previously observed in 2004-2005. This suggests that a cataclysmic collision occurred between asteroids and other objects about 20 years ago, pulverizing the bodies into fine dust particles smaller than pollen or powdered sugar, Chen said.
The Beta Pictoris galaxy
Beta Pictoris is a young galaxy located about 63 light-years from Earth in the constellation Pictor. Known to be about 20 million years old, which is significantly younger than our 4.5 billion year old solar system, Beta Pictoris is of particular interest to astronomers studying planet formation. The system is home to a prominent debris disk, indicative of ongoing planet formation, and has at least two known gas giants, Beta Pictoris b and c. The dynamical processes within Beta Pictoris, including frequent collisions and weathering in space, provide valuable insights into the early stages of planetary development and the formation of terrestrial planets.
Evidence of cataclysmic collisions
“We think all that dust is what we initially saw 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 have in fact witnessed the aftermath of a rare, cataclysmic event between large asteroid-sized bodies, marking a complete change in our understanding of this star system .”
The new data suggests that dust that was spread outward by radiation from the system’s central star is no longer detectable, Chen said. Initially, the dust near the star heated up and emitted thermal radiation that Spitzer’s instruments identified. Now dust that cooled as it moved far away from the star no longer emits these thermal signatures.
Vanishing substance phenomenon
When Spitzer collected the earlier data, scientists assumed that something like small bodies grinding downward would stir the dust and replenish the dust over time. But Webb’s new observations show that the dust disappeared and was not replaced. The amount of dust blown up is about 100,000 times greater than the asteroid that killed the dinosaurs, Chen said.
Located about 63 light-years from Earth, Beta Pictoris has long been a focal point for astronomers because of its proximity and random processes in which collisions, space weathering and other planet-shaping factors will determine the system’s fate.
Beta Pictoris: a young galaxy
At just 20 million years old – compared to our 4.5 billion year old solar system – Beta Pictoris is at a key epoch when giant planets have formed, but terrestrial planets may still be developing. It has at least two known gas giants, Beta Pic b and c, which also influence the surrounding dust and debris.
“The question we are trying to contextualize is whether this entire process of terrestrial and giant planet formation is common or rare, and the even more fundamental question: are planetary systems like the solar system that rare?” said co-author Kadin Worthen, a doctoral student in astrophysics at Johns Hopkins. “We’re actually trying to understand how weird or average we are.”
Unparalleled capabilities of the Webb telescope
The new insights also underline the Webb telescope’s unparalleled ability to reveal the complexity of exoplanets and galaxies, the team reports. They provide important clues about how the architecture of other solar systems resemble ours and will likely advance scientists’ understanding of how early unrest affects the atmosphere, water content, and other important aspects of planetary habitability.
“Most of JWST’s discoveries come from things the telescope detected directly,” said co-author Cicero Lu, a former Johns Hopkins doctoral student in astrophysics. “In this case, the story is a little different, because our results come from what JWST didn’t see.”
Collaborative research and financing
Other authors include Yiwei Chai and Alexis Li of Johns Hopkins; David R. Law, BA Sargent, GC Sloan, Julien H. Girard, Dean C. Hines, Marshall Perrin and Laurent Pueyo of the Space Telescope Science Institute; Carey 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 Rebollido of the 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.