New Insights into Star Formation from Sagittarius C in Milky Way

A recent study utilizing the James Webb Space Telescope (JWST) has unveiled crucial insights into the peculiar star formation dynamics of Sagittarius C, a region located approximately 200 light-years from the supermassive black hole at the center of the Milky Way galaxy. Despite the presence of abundant gas and dust, Sagittarius C exhibits a lower-than-expected star formation rate, a phenomenon that has puzzled astronomers for years. The research, led by a team from the University of Virginia, including undergraduate researcher Samuel Crowe and astrophysicist John Bally, highlights the significant role of magnetic fields in this galactic neighborhood.

Sagittarius C, a region rich in newborn stars and vast clouds of gas, is characterized by its unique structure formed by tangled plasma filaments shaped by magnetic forces. This finding challenges previous assumptions about star formation, as researchers expected high rates of star births in such a dense area. Instead, the JWST's findings reveal that the magnetic fields in this region may impede the star formation process, leading to an environment where the accumulation of materials does not translate into the creation of new stars.

According to Dr. John Bally, Professor of Astrophysics at the University of Virginia and co-author of the study published on June 8, 2025, in The Astrophysics Journal, "This region has the highest density of stars and massive, dense clouds of hydrogen, helium, and organic molecules. It’s one of the closest regions we know of that has extreme conditions similar to those in the young universe."

The JWST observations discovered thin, glowing filaments resembling spaghetti noodles, which were previously unpredicted by scientists. Rubén Fedriani, a postdoctoral researcher involved in the study, remarked, "We were definitely not expecting those filaments; it was a completely serendipitous discovery."

The analysis further revealed that the electromagnetic properties of plasma within Sagittarius C are indicative of nonthermal processes, suggesting that magnetic fields are essential in shaping the star-forming environment. The team measured the plasma beta, a parameter that assesses the relative strengths of thermal and magnetic pressures. The findings indicated that Sagittarius C possesses a low plasma beta, implying that magnetic pressure dominates the dynamics of this region.

These magnetic fields, generated by the movement of gas around the black hole, trap plasma into elongated filaments, significantly altering the structure of Sagittarius C compared to other star-forming regions, such as the Orion Nebula. Unlike Sagittarius C, the Orion Nebula exhibits smoother clouds and higher star formation rates, which can be attributed to the differing magnetic field strengths.

In a companion study, Crowe and Bally analyzed the life cycle of protostars within Sagittarius C, demonstrating how these young stars expel surrounding gas as they evolve. Bally noted, “Even the sun, we think, formed in a massive cluster like this. Over billions of years, all of our sibling stars have drifted away.” The study indicates that Sagittarius C is nearing the end of its life as a stellar nursery, with its gas supply diminishing due to the energy output from newborn stars.

The research represents a significant advancement in understanding the complexities of star formation, particularly in extreme environments like Sagittarius C. By shedding light on the intricate interplay between magnetic forces and star formation, these findings have implications not only for the Milky Way but for other galaxies as well. As JWST continues to gather data, the scientific community anticipates further revelations about the fundamental processes governing star formation across the universe.

In summary, the insights gained from Sagittarius C underscore the importance of magnetic fields in galactic dynamics and challenge long-held assumptions regarding star formation in proximity to supermassive black holes. The ongoing exploration of such regions promises to enhance our understanding of galactic evolution and the formation of stars in diverse cosmic conditions.