The James Webb Space Telescope (JWST) has made significant strides in addressing fundamental questions in cosmology, particularly regarding the formation of planets in the early universe. Recent observations have provided insights into a perplexing discovery made by the Hubble Space Telescope (HST) in 2003, which revealed a massive planet orbiting a star that existed just 1 billion years after the Big Bang. This finding contradicted established models of planet formation, which suggested that early stars lacked sufficient heavy elements necessary for planet creation.
Led by Guido De Marchi from the European Space Research and Technology Centre (ESTEC), an international team of scientists utilized JWST to study stars in the Small Magellanic Cloud (LMC). Their research, published on December 16 in The Astrophysical Journal, indicates that protoplanetary disks around these stars have longer lifespans than previously thought, potentially allowing for the formation of planets in environments with fewer heavy elements.
According to current cosmological models, the first stars, known as Population III stars, formed approximately 13.7 billion years ago. These stars, primarily composed of hydrogen and helium, exploded in supernovae, dispersing heavier elements that later contributed to the formation of subsequent star generations and planetary systems. The Hubble's discovery of a massive planet—2.5 times the mass of Jupiter—around an ancient star raised questions about the timeline and conditions necessary for planet formation.
Elena Sabbi, chief scientist at the Gemini Observatory, noted that existing models suggested that protoplanetary disks in such environments should dissipate quickly, preventing planets from growing large. However, JWST's observations of the star cluster NGC 346 revealed that many young stars still possess protoplanetary disks at ages of 20 to 30 million years, contradicting previous assumptions.
De Marchi emphasized the significance of these findings, stating that they confirm Hubble's controversial observations and challenge long-accepted models of planet formation. The team proposed two mechanisms to explain the longevity of these disks: one suggests that radiation pressure from stars is less effective in environments with fewer heavy elements, while the other posits that stars forming from larger gas clouds could create more massive disks that take longer to dissipate.
As JWST continues to provide groundbreaking insights, these findings underscore the need to reevaluate our understanding of planet formation and the evolution of the universe. The telescope's ability to confirm and expand upon Hubble's discoveries is reshaping astronomical theories and paving the way for future research.