A young and giant star that is forming on the outer edge of our Milky Way just made itself known in spectacular fashion – by beaming a huge jet of gas across 8 light-years of interstellar space. That’s almost twice the distance from our Sun to Alpha Centauri, the next closest star system.
NASA’s James Webb Space Telescope (JWST) happened to catch the event in action, and what it saw has scientists buzzing.
The eruption, which tears through space at hundreds of thousands of miles per hour, looks like something out of Star Wars – a double-bladed lightsaber made of pure plasma.
But this isn’t science fiction. This is a real, powerful stream of gas being flung out from a forming star that already weighs ten times as much as our Sun.
Massive jet from a giant star
This wasn’t something astronomers planned to find. The discovery happened during unrelated observations, and it took even the experts by surprise.
The outflow – technically called a “jet” – is extremely rare for a star this massive. Most similar jets come from small stars.
“We didn’t really know there was a massive star with this kind of super-jet out there before the observation. Such a spectacular outflow of molecular hydrogen from a massive star is rare in other regions of our galaxy,” said Yu Cheng of the National Astronomical Observatory of Japan.
“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 Chalmers University of Technology in Sweden.
The mechanics behind a stellar eruption
So what’s actually happening here? When stars form, they pull in huge amounts of gas and dust from their surroundings.
But not all that material makes it to the surface. Some of it gets shot back out, blasting away along the poles of the spinning star, likely driven by magnetic fields.
These supercharged jets are like the star’s version of a birth cry – an announcement that something big has arrived.
The jets don’t just happen randomly – they carry traces of the star’s entire growth history. As the forming star gathers mass, the surrounding material channels into a disk that rotates rapidly.
Along the poles of this spinning system, the jet shoots outward in both directions. Over time, the oldest parts of the jet stretch farthest into space, while newer bursts stay closer to the source.
“Originally the material was close into the star, but over 100,000 years the tips were propagating out, and then the stuff behind is a younger outflow,” said Tan.
Stellar nursery on the edge
This jet isn’t happening anywhere near Earth. It’s coming from a star cluster called Sharpless 2-284, located 15,000 light-years away.
That’s about twice as far from the center of the Milky Way as our Sun is. It’s out on the fringes, in a quiet, less-developed corner of the galaxy.
That part of space has fewer heavy elements – things like carbon, oxygen, and iron – than areas closer to the galactic center, and it’s a big deal because the early universe was also low in these elements.
“Massive stars, like the one found inside this cluster, have very important influences on the evolution of galaxies,” said Cheng.
“Our discovery is shedding light on the formation mechanism of massive stars in low metallicity environments, so we can use this massive star as a laboratory to study what was going on in earlier cosmic history,” Cheng explained.
Old debate about giant star jets
For decades, astronomers have argued over how giant stars form. There are two leading theories. One says they grow in a steady, stable way, through a process called core accretion.
The other says it’s more chaotic, with gas falling in from different directions in a competition between stars.
Now, new observations from Webb offer strong support for the more stable model.
“Webb’s new images are telling us that the formation of massive stars in such environments could proceed via a relatively stable disk around the star that is expected in theoretical models of star formation known as core accretion,” said Tan.
“However, 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. That tells us that this central disk is held steady and validates a prediction of the core accretion theory,” he added.
Waiting to see what’s next
The star behind the jet is still growing. The Webb team used new theoretical models to match what they saw and figure out what kind of star could be launching the jet.
Everything points to a massive, still-forming star that’s busy pulling in more material and blasting out excess energy.
Other stars in the same area might not be far behind. Data from the Atacama Large Millimeter Array in Chile has already found another dense core nearby – one that could give birth to another massive star soon.
The discovery shows that the outer edges of our galaxy, while often overlooked, may be full of surprises. And thanks to Webb’s sharp eyes, we’re finally seeing them.
The full study was published in the journal The Astrophysical Journal.
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