NASA’s Webb Telescope Uncovers a 30-Million-Year-Old Planet Factory That Shouldn’t Exist

Astronomers have long believed that the swirling disks of gas and dust that form planets around young stars last only about 10 million years. However, a groundbreaking discovery shows that for certain low-mass stars, these disks can endure far longer — up to 30 million years.

Observations using NASA’s James Webb Space Telescope reveal a stable, gas-rich environment around such stars, raising intriguing possibilities for extended planet formation. This could have major implications for our understanding of planetary evolution and the potential for life beyond Earth, particularly in systems like TRAPPIST-1, where planets may have had extra time to form in habitable zones.

Snapshots of the Universe’s Planetary Nurseries

If the universe had a photo album, it would likely feature images of swirling disks of gas and dust — planetary nurseries forming around young stars. These planet-forming disks are thought to be a common but short-lived stage in the life of most young stars, supplying the raw materials needed to build planets.

Typically, these disks last about 10 million years before dispersing, a brief existence in cosmic terms. However, researchers at the University of Arizona have made a surprising discovery: some disks can persist far longer than expected. Their findings show that around very small stars, just one-tenth the mass of the Sun or less, these disks can survive much longer than previously thought.

Breaking the Limits: A 30-Million-Year-Old Disk

In a study published in the Astrophysical Letters Journal, a team led by Feng Long from the University of Arizona’s Lunar and Planetary Laboratory detailed the observation of a 30-million-year-old protoplanetary disk—three times older than what scientists typically expect. Using NASA’s James Webb Space Telescope, they conducted the first detailed chemical analysis of a long-lived disk, offering new clues about planet formation and the potential for habitable worlds beyond our solar system.

“In a sense, protoplanetary disks provide us with baby pictures of planetary systems, including a glimpse of what our solar system may have looked like in its infancy,” said Long, the paper’s lead author and a Sagan Fellow with the Lunar and Planetary Laboratory.

How Stars Control the Lifespan of Their Disks

As long as the star has a certain mass, high-energy radiation from the young star blows the gas and dust out of the disk, and it can no longer serve as raw material to build planets, Long explained.

The team observed a star with the official designation WISE J044634.16–262756.1B – more conveniently known as J0446B – located in the constellation Columba (Latin for “dove”) about 267 light-years from Earth. The researchers found that its planet-forming disk has lasted about three times longer than expected.

“Although we know that most disks disperse within 10 million to 20 million years, we are finding that for specific types of stars, their disks can last much longer,” Long said. “Because materials in the disk provide the raw materials for planets, the disk’s lifespan determines how much time the system has to form planets.”

Why Chemical Stability Matters for Planet Formation

Even though tiny stars retain their disks longer, their disk’s chemical makeup does not change significantly. The similar chemical composition regardless of age indicates that the chemistry does not change drastically even as a disk reaches an advanced age. Such a long-lived, stable chemical environment could provide planets around low-mass stars with more time to form.

By analyzing the disk’s gas content, the researchers ruled out the possibility that the disk around J0446B is a so-called debris disk, a longer-lasting type of disk that consists of second-generation material produced by collisions of asteroid-like bodies.

“We detected gases like hydrogen and neon, which tells us that there is still primordial gas left in the disk around J0446B,” said Chengyan Xie, a doctoral student at LPL who also contributed to the study.

What Long-Lived Disks Mean for Life Beyond Earth

The confirmed existence of long-lived disks rich in gases has implications for life outside our solar system, according to the authors. Of particular interest to researchers is the TRAPPIST-1 system, located 40 light-years from Earth, consisting of a red dwarf star and seven planets similar in size to Earth. Three of those planets are located in the “habitable zone,” where conditions allow for liquid water to exist and offer the potential for life to form, at least in principle.

Because stars with long-lived planetary disks fall into a similar mass category as the central star in the TRAPPIST-1 system, the existence of long-lived disks is especially interesting for the evolution of planetary systems, say Long and her co-authors.

“To make the specific arrangement of orbits we see with TRAPPIST-1, planets need to migrate inside the disk, a process that requires the presence of gas,” said Ilaria Pascucci, a professor of planetary sciences at LPL who co-authored the study. “The long presence of gas we find in those disks might be the reason behind TRAPPIST-1’s unique arrangement.”

What Long-Lived Disks Reveal About the Cosmos

Long-lived disks have not been found for high-mass stars such as the sun, since stars in such systems evolve much more quickly and planets have less time to form. Although our solar system took a different evolutionary route, long-lived disks can tell researchers a lot about the universe, the authors noted, because low-mass stars are believed to vastly outnumber sun-like stars.

“Developing a better understanding of how low-mass star systems evolve and getting snapshots of long-lived disks might help pave the way to filling out the blanks in the photo album of the universe,” Long said.

Reference: “The First JWST View of a 30-Myr-old Protoplanetary Disk Reveals a Late-stage Carbon-rich Phase” by Feng Long, Ilaria Pascucci, Adrien Houge, Andrea Banzatti, Klaus M. Pontoppidan, Joan Najita, Sebastiaan Krijt, Chengyan Xie, Joe Williams, Gregory J. Herczeg, Sean M. Andrews, Edwin Bergin, Geoffrey A. Blake, María José Colmenares, Daniel Harsono, Carlos E. Romero-Mirza, Rixin Li, Cicero X. Lu, Paola Pinilla, David J. Wilner, Miguel Vioque and Ke Zhang, 6 January 2025, The Astrophysical Journal Letters.
DOI: 10.3847/2041-8213/ad99d2

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