New data from the James Webb Space Telescope challenges our understanding of planet formation in the early days of the universe. Researchers used Webb to study stars in a nearby galaxy that, like the early universe, lacks large amounts of heavy elements. They found that some stars have planet-forming discs, which are even longer-lived than those seen around young stars in the Milky Way galaxy.
The discovery was made possible by comparing data from Webb with observations from the Hubble Space Telescope. In 2003, Hubble spotted a massive planet around an old star, implying that some planets formed when the universe was very young. However, this raised questions about how such planets could form given the lack of heavier elements.
To answer this question, researchers re-examined stars in the Small Magellanic Cloud, a dwarf galaxy nearby to the Milky Way. They found that massive, star-forming clusters like NGC 346 have planet-forming discs that persist for longer than predicted by current theoretical models.
According to study leader Guido De Marchi, “With Webb, we have a strong confirmation of what we saw with Hubble.” The discovery refutes previous predictions that the star would quickly blow away the disc when there are few heavier elements. Instead, researchers propose two possible mechanisms for planet-forming discs to persist in environments scarce in heavier elements.
The first mechanism suggests that it takes longer for a star in a poor element environment to disperse its disc. The second possibility is that a Sun-like star must form from a larger cloud of gas when there are few heavier elements, producing a bigger disc that persists for longer.
This finding has significant implications for how planets form and the type of planetary systems that can exist in different environments.
Source: https://www.esa.int/Science_Exploration/Space_Science/Webb/Planet-forming_discs_lived_longer_in_early_Universe