The theory, published in the Monthly Notices of the Royal Astronomical Society, explains long-standing mysteries surrounding the chemical history and structure of the solar system, including the presence of rare isotopes in meteorites and the existence of water-rich planetesimals.
The astronomers modeled the conditions necessary for the formation of a bubble of gas and dust in a region containing a massive star. The bubble forms as the strong radiation from the star pushes matter away, creating an envelope that traps its own radiation and becomes hot.
Inside this high-temperature environment, dust grains become sticky, allowing them to clump and condense into planetesimals—the building blocks of planets—and asteroids, creating bodies with rare isotopic compositions.
According to the scientists, this high-temperature environment can explain why meteorites contain rare isotopes such as 26Al and 60Fe. These isotopes have extremely short half-lives and must have been produced very shortly—around one million years—before their incorporation into solid material in order to have survived to the present day.
At the same time, the bubble shields the protoplanetary disk—where new planets are forming—from the harsh radiation of the central star. This would enable complex prebiotic molecules necessary for life to form, while leaving the inner regions of the disk warm enough for water-based chemistry.
The research challenges the traditional view of solar system formation, which proposes the process begins with material accumulating in a cool molecular cloud.
The scientists point out that their new theory is consistent with recent discoveries of giant molecular bubbles in star-forming regions and suggest the idea should be further explored by comparing predicted chemical compositions with observations of protoplanetary disks around young stars.
