In 2003, Hubble detected evidence of a massive planet around an ancient star, which puzzled astronomers because such stars in the early universe lacked the heavier elements essential for planet formation. Current models predicted that the disks around these stars had short lifetimes, insufficient for massive planet formation.

To investigate further, astronomers studied the star-forming region NGC 346, a nearby proxy for the early universe. Hubble observed signs of planet-forming disks around stars 20 to 30 million years old, much older than theories predicted these disks could survive. But without detailed spectra, scientists couldn't be sure these disks could form planets.

Using Webb's advanced spectroscopic capabilities, researchers have now confirmed the presence of long-lived planet-forming disks in NGC 346. This finding supports Hubble's results and challenges current models and suggests planet formation in the early universe occurred differently than previously thought.

In the early universe, stars were mainly composed of hydrogen and helium. Current theories suggest that with a scarcity of heavier elements, like carbon and iron, the disks around these stars would have very short lifespans, too brief for larger planets to form. However, Hubble and JWST's observations indicate that some stars in environments similar to the early universe do have planet-forming disks.

Guido De Marchi of the European Space Research and Technology Centre, who led this study and is lead author on the new paper in The Astrophysical Journal, said: “We see that these stars are indeed surrounded by disks and are still in the process of gobbling material, even at the relatively old age of 20 or 30 million years. This also implies that planets have more time to form and grow around these stars than in nearby star-forming regions in our own galaxy."

Dr Olivia Jones, STFC Webb Fellow at UK ATC and co-author on the new paper, said: “This discovery supports the controversial Hubble findings, which means we need to re-examine current theories on planet formation. It shows us that planet formation in the early universe was much more complex and enduring than we previously believed. Once again JWST is helping to unveil new information on how the Universe formed."

Find out more.

Read the Astrophysical Journal paper.