Interstellar Objects might potentially be Key to Forming Gas Giant Planets, New Research Suggests
A new study indicates that interstellar objects, those originating outside our solar system, could act as “seeds” for planet formation, particularly around larger stars, resolving long-standing mysteries about how gas giants arise.
The discovery of interstellar visitors like 1I/’Oumuamua, 2I/Borisov, and most recently 3I/ATLAS, has revealed a surprisingly large population of these objects traversing the galaxy. Their prevalence suggests they are also present within protoplanetary disks – the swirling clouds of dust and gas where planets are born. A colorized image of interstellar comet 3I/ATLAS, captured by the CaSSIS instrument aboard ESA’s Trace Gas Orbiter on October 3, 2025, provides a stunning visual of one such traveler.
Why did this research come about?
The research emerged from observations of interstellar objects-1I/’Oumuamua,2I/Borisov,and 3I/ATLAS-revealing a larger-than-expected population. This prompted scientists to consider their role in planet formation,specifically addressing challenges in the standard accretion model.
Since 2017, astronomers have identified three interstellar objects passing through our solar system, offering a glimpse into this previously unknown population.But their importance may extend far beyond mere observation.According to a researcher at Forschungszentrum Jülich,”interstellar objects may be more influential than they at first appear to be.”
The standard model of planet formation relies on accretion, where tiny particles gradually clump together to form larger bodies. however, a meaningful hurdle exists: theorists have struggled to explain how these particles overcome the “1-meter barrier,” where collisions tend to result in bouncing or shattering rather than sticking. Interstellar objects offer a potential solution.
Who conducted this research?
the research was led by a researcher at Forschungszentrum Jülich, though the article doesn’t name the specific individual. The findings were presented at the EPSC-DPS2025 Joint Meeting.
New models demonstrate that protoplanetary disks could gravitationally capture millions of interstellar objects, similar in size to 1I/’Oumuamua – estimated to be around 100 meters (328 feet) long. “interstellar space would deliver ready-made seeds for the formation of the next generation of planets,” the researcher explained. These captured objects bypass the 1-meter barrier, providing a solid foundation for rapid growth.
This theory also addresses another puzzle: the relative scarcity of gas giant planets like Jupiter around M dwarfs, the smallest and coolest stars. these planets are far more common around stars similar in mass to our Sun. The challenge lies in the limited lifespan of protoplanetary disks around Sun-like stars – roughly two million years – making it difficult to form gas giants within that timeframe.
The presence of interstellar object “seeds” accelerates the process. If these objects are already present within the disk, they provide a nucleus for material to accrete, allowing gas giants to form more quickly. “Higher-mass stars are more efficient in capturing interstellar objects in their disks,” the researcher noted. “Thus, interstellar object-seeded planet formation should be more efficient around these stars, providing a fast way to form giant planets.”
What is the main finding of this research?
The main finding is that interstellar objects can act as “seeds” for planet formation, particularly gas giants, by bypassing the 1-meter barrier in accretion and accelerating the process, especially around larger stars.
And, crucially, “their fast formation is exactly what we have observed.”
The findings, presented in september 2025 at the EPSC-DPS2025
