JWST study of 72 young stars reveals how planet-forming gas escapes over time

September 28, 2026 at 05:32 PM2 min

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NASA's James Webb Space Telescope observed 72 young, Sun-like stars to trace how gas escapes protoplanetary disks. The study, led by Naman Bajaj of the University of Arizona, found that different wind mechanisms dominate at different stages of disk evolution. The findings, published in The Astronomical Journal, suggest that disk gas dispersal sets a fundamental clock for planet formation.

Key Facts

The study examined 72 young, Sun-like stars and their protoplanetary disks, making it one of the largest planet-formation studies conducted with JWST.
The research was led by Naman Bajaj of the University of Arizona and coauthored by SETI Institute scientist Uma Gorti.
The findings were published in The Astronomical Journal.
The team used JWST's Mid-Infrared Instrument (MIRI) to trace molecular hydrogen and ionized neon as indicators of escaping gas.
In 2020, LPL professor Ilaria Pascucci led a related study that predicted molecular winds dense enough to block X-ray photons during the earliest stages.

Disk Gas Loss Mechanisms

The study suggests that different kinds of winds dominate at different stages of a planetary system's early development. Researchers concentrated on molecular hydrogen, the most abundant molecule in protoplanetary disks, and ionized neon as indicators of escaping material. JWST's sensitivity and resolution allowed the team to distinguish broad winds containing molecular hydrogen from jets and winds traced by neon. Before JWST, researchers could not directly observe molecular hydrogen, but the team predicted that molecular winds should exist and could be dense enough during the earliest stages to block X-ray photons. By directly tracing molecular hydrogen in the new observations, Bajaj's team confirmed those predictions with JWST images.

Planet Formation Deadline

Disk dispersal sets a fundamental clock for planet formation: once the gas is gone, the opportunity to build gas-rich planets is essentially over, said SETI Institute scientist Uma Gorti. Our solar system is now about 4.5 billion years old and consists mostly of empty space. During its first few million years, the young Sun was surrounded by a dense protoplanetary disk containing roughly 100 times more gas than dust. Nearly all of that gas eventually disappeared. Understanding when and how this material is lost matters because gas is essential for forming giant planets such as Jupiter and Saturn.