Astronomers have made a remarkable discovery that sheds new light on how stars are born.
Using the powerful Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, a team has captured the first detailed look at protostellar jets—narrow streams of gas blasting out of a newborn star—in one of the farthest reaches of our galaxy.
The object in focus is a protostar called Sh 2-283-1a SMM1, located about 26,000 light-years from the sun and more than 51,000 light-years from the galactic center.
This part of the Milky Way contains far fewer heavy elements—about one-third of what is found near the sun. Such conditions resemble those of the early Milky Way, offering astronomers a rare chance to study star formation in a more primitive environment.
ALMA’s observations revealed a striking picture: a bipolar system with thin, high-speed jets shooting out from the protostar, surrounded by wider, slower-moving outflows. The colors of the gas, tracked as blue- and red-shifted contours, showed material moving toward and away from Earth.
One of the most surprising results was that these jets are not steady. Instead, the protostar ejects bursts of material every 900 to 4,000 years.
This stop-and-start rhythm, known as episodic ejection, helps regulate the star’s growth.
By occasionally expelling gas and angular momentum, the protostar can continue to gather material from its disk without collapsing under the strain. Episodic ejections had been observed in nearby star-forming regions before, but this is the first time they’ve been clearly identified so far out in the galaxy.
“By resolving jets and outflows in a protostar this far from the galactic center, we see that the same basic physics of star formation applies everywhere,” explained lead author Toki Ikeda of Niigata University.
“But the chemistry tells a different story.”
Indeed, the chemical makeup of the outflows reflects the unusual environment. Measurements of molecules like carbon monoxide (CO) and silicon monoxide (SiO) revealed a lower SiO-to-CO ratio compared with protostars closer to the sun. This suggests that shocks and dust behave differently in low-metallicity regions, where heavy elements are scarce.
The team also found that Sh 2-283-1a SMM1 is a hot core—a compact, warm, and chemically rich region around a forming star.
This is only the second hot core ever detected in the outer galaxy, highlighting just how rare such chemically complex regions are so far from the center. The protostar itself is estimated to shine with 6,700 times the luminosity of the sun, placing it in the intermediate-to-high-mass category. Even more exciting, it harbors complex organic molecules, hinting at the potential for chemical richness in unexpected places.
Beyond this single object, ALMA also identified outflows from four other protostars in the outer Milky Way, proving that star formation there is both active and widespread.
This breakthrough not only extends the frontier of where astronomers can study jets and outflows, but also shows that while chemistry may vary depending on the environment, the underlying physics of star birth is universal.
In other words, the same processes shaping stars today in the Milky Way’s outskirts were likely at work in the early universe, linking our galaxy’s present to its ancient past.
