A star factory at the heart of our galaxy is mysterious and important

About 200 light-years from the black hole at the center of the Milky Way lies a region that isn't as fertile as scientists would think. 

This star-forming cloud of gas and dust, Sagittarius C, is brimming with all of the material to make star babies, yet its yield of new stars remains relatively low, despite the fact that it has likely birthed thousands of stars already. Scientists pointed the James Webb Space Telescope, a collaboration of NASA and its European and Canadian space counterparts, at this mysterious stellar nursery to try to figure out why. With its powerful infrared vision, the telescope was able to give a clearer picture. 

The findings, published in The Astrophysical Journal in two papers, provide new insights into why some star-forming clouds may appear relatively impotent. Researchers now believe strong magnetic fields may be responsible for the lack of output.

"A big question has been, if there is so much dense gas and dust here, and we know stars form in these kinds of clouds, why are so few stars born in Sagittarius C?" said John Bally, an astrophysicist at the University of Colorado Boulder, in a statement. "For the first time, we are seeing that strong magnetic fields may be playing a major role in stopping star formation."

The Meerkat radio telescope in South Africa puts the Webb image in context by showing Sagittarius C in an environment spanning 1,000 light-years. The inset Webb image covers about 44 light-years. Credit: NASA / ESA / CSA / STScI / SARAO / Samuel Crowe / John Bally / Ruben Fedriani / Ian Heywood

Webb was built to detect invisible light at infrared wavelengths. Cosmic dust and gas obscure the view to extremely distant and inherently dim light sources, but infrared waves can pierce through the clouds. One Webb scientist likened the strength of the telescope to being able to sense the heat of a single bumblebee on the moon.

Scientists say understanding what's going on in Sagittarius C is an important step in understanding star formation generally. Stars create most of the chemical elements on Earth, including carbon and oxygen, which are essential ingredients for life. But even experts admit they have much to learn about how the universe makes new stars. 

The researchers confirmed that two enormous stars, each more than 20 times the mass of the sun, are growing inside Sagittarius C, blasting out powerful jets of gas as they develop. They also identified five smaller stars swaddled in thick layers of dust. 

Dust and gas obscure the view to extremely distant and inherently dim light sources, but infrared waves can pierce through the clouds. Credit: NASA GSFC / CIL / Adriana Manrique Gutierrez illustration

Webb also detected 88 weird structures made of glowing hydrogen, thought to be shock waves caused by young stars tossing out their own material into space. Additionally, scientists discovered an entirely separate nearby star factory with at least two of its own growing stars.

Prior to these studies, Sagittarius C showed dozens of threadlike filaments, some several light-years long, in hot hydrogen gas surrounding the main star-forming cloud. Scientists think magnetic forces of the Milky Way's supermassive black hole, Sagittarius A*, might be strong enough to push against the pull of gravity. Perhaps such tension could prevent the dense clouds from collapsing and forming more stars.

Samuel Crowe, a Rhodes Scholar at the University of Virginia who co-led the study, said Sagittarius C has turned out to be an important laboratory for testing theories on star formation.

"This discovery opens up new questions about how magnetic fields influence the birth of stars," he said in a statement, "both in our galaxy and beyond."