JWST reveals a race against time for forming planets

A new study using NASA’s James Webb Space Telescope (JWST) reveals how gas in protoplanetary disks escapes, offering insights into the timing and mechanisms of planet formation. The research, led by Naman Bajaj from the University of Arizona and co-authored by SETI Institute scientist Uma Gorti, examined 72 young stars and their disks, providing one of the largest planet-formation studies using JWST. The findings show that different types of winds are more important at different stages in a planetary system’s early life, with molecular hydrogen and ionized neon serving as indicators of gas expulsion.

The study found that in 66 of the 72 disks, there were extended emissions from molecular hydrogen and ionized neon, with conical molecular hydrogen winds in 46 systems and fast-moving neon jets in 40. These observations help scientists understand how gas is removed from disks and how this process changes over time. The research confirms predictions made in 2020, where the team traced molecular hydrogen directly, confirming the existence of molecular winds and their ability to block X-ray photons. This new study connects theoretical work with what astronomers can now see across dozens of planetary systems, showing how photoevaporation becomes increasingly important as disks age and magnetic winds weaken.

The results indicate that no single process controls how a planet-forming disk disappears. Instead, planetary systems seem to move from an early stage with strong, magnetically driven jets and winds to a later stage where atomic winds, including photoevaporative winds, play a bigger role. This shift directly affects how planets form, as gas giants like Jupiter must assemble their massive atmospheres while the disk is still substantial enough to supply them before winds and jets carry that raw material away into space. The study found that the timing and extent of gas removal are critical for planet formation, with the race against time being a key factor in the development of planets.

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