By Bethany Lee | 2025-10-30

NASA’s James Webb Space Telescope has revealed an enormous stellar jet shooting from a protostar 15,000 light years away, on the edge of the Milky Way.

The stellar jet is made up of rays of plasma spreading eight light years long and located in a nebula known as Sharpless 2-284 (Sh2-284).

These protostellar jets act like a "birth announcement" for new stars, according to NASA, shooting out during the accumulation of gas and dust that will eventually become a solar system.

Although hundreds of stellar jets have been observed in low-mass stars in the past, scientists say this particular jet is remarkable for its length and size.

Its central star weighs about 10 times as much as our sun, and the surrounding explosion is millions of times larger than our solar system.

"I was really surprised at the order, symmetry, and size of the jet when we first looked at it," said Jonathan Tan of the University of Virginia and the Chalmers University of Technology in Gothenburg, Sweden.

Tan is co-author of a new paper presenting the low-metallicity Star Formation (LZ-STAR) survey of Sh2-284 that has been accepted for publication in The Astrophysical Journal.

The paper shows that besides producing a cosmic explosion worthy of a science fiction movie, the protostar and its stellar jets provide evidence to support a scientific theory of star formation: the core accretion model.

Core accretion model

The core accretion model predicts that a star forms from a single dense core of gas and dust. As the core collapses under gravity, it spins and flattens into a stable disk that eventually becomes the star and its surrounding system.

This model is widely accepted for the formation of low- and medium-mass stars. But scientists debate whether it also applies to very massive stars (VMS).

An alternative theory, called competitive accretion, suggests that massive stars grow in a more chaotic way, gaining much of their mass from the surrounding environment instead of from one central core.

The observation of this massive protostellar jet in Sh2-284 with highly symmetrical rays seems to suggest that even large stars formed according to the core accretion model.

It shows the more massive the star at the center, the larger the resulting jets.

"What we’ve seen here, because we’ve got the whole history -- a tapestry of the story -- is that the opposite sides of the jets are nearly 180 degrees apart from each other," Tan said.

"That tells us that this central disk is held steady and validates a prediction of the core accretion theory," he explained.

Studying star formation

The Sh2-284 discovery is a major advancement for scientists studying star formation at our universe’s inception.

Scientists believe Sh2-284, located on the edge of the Milky Way, resembles the environment of the early universe because of its relatively low metallicity, or the concentration of elements heavier than helium and hydrogen.

For that reason, it’s a good model for how large stars grew and formed then.

"We can use this massive star as a laboratory to study what was going on in earlier cosmic history," said the study's lead author, Yu Cheng, of the National Astronomical Observatory of Japan.

The Sh2-284 study also presented data from the Atacama Large Millimeter Array (ALMA) in Chile, which found another stellar core.

This core has not yet released a stellar jet, but it is a sign that the enormous protostar in Sh2-284 may not be the only one forming on our galaxy's outskirts.

ALMA, the largest astronomical project in existence, is a telescope composed of 66 high-precision antennas located on the Chajnantor plateau in northern Chile.

The project is an international partnership of scientific and research entities from Europe, the United States and Japan, with institutions based in Canada, Taiwan and Korea, in cooperation with Chile.