Webb Telescope reveals planet-forming disks persisted longer in the early universe

The James Webb Space Telescope has confirmed a long-standing mystery about planet formation in the early universe, revealing that planet-forming disks around young stars lasted far longer than scientists previously believed, even in environments with low heavy-element content.

These findings, recently published in The Astrophysical Journal, offer groundbreaking insights into planetary evolution.

The mystery dates back to 2003 when the Hubble Space Telescope discovered massive planets orbiting ancient stars that lacked heavy elements like carbon and iron - critical ingredients for planet formation. This raised questions about how planets could emerge and grow under such conditions.

To investigate, the Webb Telescope turned its attention to NGC 346, a dense star cluster in the Small Magellanic Cloud, a neighboring galaxy with a chemical composition similar to the early universe. In this low-metal environment, Webb found that planet-forming disks persisted around stars for 20–30 million years - far longer than the few million years observed in our Milky Way.

Guido De Marchi, lead researcher from the European Space Research and Technology Centre (ESTEC), explained that these disks are not only still present but actively accumulating material, challenging current models that predict rapid disk dispersal. Co-investigator Elena Sabbi of NOIRLab’s Gemini Observatory emphasized that such longevity was unexpected in environments with low metallicity, where heavy elements are scarce.

Scientists propose two possible reasons for the extended survival of these disks. One is weaker radiation pressure. In low-metal environments, radiation pressure - which typically disperses disks - has less impact because heavier elements are needed for effective gas interaction. Second is larger gas clouds. Stars in such environments may form from bigger gas clouds, leading to larger disks that naturally take longer to dissipate.

The Webb Telescope's observations provide compelling evidence that planet formation in the early universe could persist for extended periods, even under seemingly unfavorable conditions. These findings reshape traditional theories, demonstrating the resilience of planet-forming disks and offering new clues about how planets evolved during the universe's infancy.