NASA/ESA/CSA The James Webb Space Telescope has confirmed a decades-old mystery regarding planet formation in the early universe. According to The Astrophysical Journal, the findings indicate that planet-forming disks around stars last much longer than previously thought, even in environments with minimal heavy elements.
Reportedly, in 2003, the NASA/ESA Hubble Space Telescope observed the presence of giant planets around ancient stars. This was surprising because these stars lacked the heavy elements like carbon and iron needed for planet formation. This discovery raised the question of how such planets could form and evolve so early in the history of the universe.
Revisiting a long-standing puzzle
To learn more, the Webb telescope focused on NGC 346, a giant star cluster in the Small Magellanic Cloud. As one of the galaxy’s closest neighbors, its chemical composition, dominated by hydrogen and helium, closely resembles the conditions in the early universe. The stars in the cluster, estimated to be 20 to 30 million years old, were found to retain planet-forming disks much longer than the expected time frame observed in our Galaxy.
Findings challenge existing models
Study lead Guido De Marchi, of the European Space Research and Technology Center (ESTEC), told ESA sources that they see that the disks actually surround these stars and are still in the process of swallowing material, even That is even at a relatively young age of 20 years or 30 million years. The discovery challenges existing models, which predict that the planet-forming disk will collapse within a few million years. Elena Sabbi, co-investigator and chief scientist at NOIR Lab’s Gemini Observatory, explained in a statement that models suggested the disk would not survive in an environment with low metal content. Webb has now proven that under such conditions planets can form and evolve over long periods of time.
Why do discs last longer?
Two possible explanations for the extended lifetime of these discs have been proposed. The first suggests that radiation pressure, which normally expands the disk, is less effective in an atmosphere with minimal heavy elements. These elements are needed to efficiently interact with the surrounding gas for radiation.
The second explanation considers the initial size of the gas clouds. Stars forming in low-metal environments may originate from large clouds of gas, forming large disks. Larger disks take much longer to expand, allowing more time for planet formation.
Implications for planet formation theories
These observations provide new insight into planet formation in the early universe, indicating that planetary evolution periods can extend even under conditions once thought to be unfavorable. With Webb’s unprecedented resolution, astronomers now have solid evidence that planet-forming disks are far more flexible than previously understood, reshaping long-held theories about planetary evolution.
