Free Astronomy Magazine July-August 2025

15 JULY-AUGUST 2025 ASTRO PUBLISHING Sagittarius C have been hinted at in past observations, but this is the first time we’ve been able to con- firm them in infrared light. It’s very exciting to see, because there is still a lot we don’t know about star for- mation, especially in the Central Molecular Zone, and it’s so impor- tant to how the universe works,” said Crowe. Webb’s 2023 image of Sagittarius C showed dozens of distinctive fila- ments in a region of hot hydrogen plasma surrounding the main star- forming cloud. New analysis by Bally and his team has led them to hy- pothesize that the filaments are shaped by magnetic fields, which have also been observed in the past by the ground-based observatories ALMA and MeerKAT (formerly the Karoo Array Telescope). “The mo- tion of gas swirling in the extreme tidal forces of the Milky Way’s su- permassive black hole, Sagittarius A*, can stretch and amplify the surrounding magnetic fields. Those fields, in turn, are shaping the plasma in Sagittarius C,” said Bally. The researchers think that the mag- netic forces in the galactic center may be strong enough to keep the plasma from spreading, instead con- fining it into the concen- trated filaments seen in the Webb image. These strong magnetic fields may also resist the gravity that would typi- cally cause dense clouds of gas and dust to collapse and forge stars, explaining Sagittarius C’s lower-than- expected star formation rate. “This is an exciting area for future research, as the influence of strong magnetic fields, in the cen- ter of our galaxy or other galaxies, on stellar ecology has not been fully consid- ered,” said Crowe. O n the previous page: Labeling, compass arrows, and scale bars provide con- text for these MeerKAT and James Webb Space Telescope images. The star- forming region Sagittarius C, captured by the James Webb Space Telescope, is about 200 light-years from the Milky Way’s central supermassive black hole, Sagittarius A*. Huge vertical filamentary structures in the MeerKAT radio data echo those Webb captured on a smaller scale, in infrared, in a blue-green hydro- gen cloud. Astronomers think the strong magnetic fields in the heart of the galaxy are shaping the filaments. The spectral index at the lower left shows how color was assigned to the radio data to create the image. On the negative end, there is non-thermal emission, stimulated by electrons spiraling around magnetic field lines. On the positive side, thermal emission is coming from hot, ionized plasma. For Webb, color is assigned by shifting the infrared spectrum to visible light colors. The shortest infrared wavelengths are bluer, and the longer wave- lengths appear more red. [NASA, ESA, CSA, STScI, SARAO, Samuel Crowe (UVA), John Bally (CU), Ruben Fedriani (IAA-CSIC), Ian Heywood (Oxford)] “The extreme environment of the galactic center is a fascinating place to put star formation theories to the test, and the infrared capabilities of NASA’s James Webb Space Telescope provide the opportunity to build on past important observations from ground-based telescopes like ALMA and MeerKAT,” said Samuel Crowe, another principal investigator on the research, a senior undergradu- ate at the University of Virginia and a 2025 Rhodes Scholar. Bally and Crowe each led a paper published in The Astrophysical Journal . In Sagittarius C’s brightest cluster, the researchers confirmed the tenta- tive finding from the Atacama Large Millimeter Array (ALMA) that two massive stars are forming there. Along with infrared data from NASA’s retired Spitzer Space Telescope and SOFIA (Stratospheric Observatory for Infrared Astronomy) mission, as well as the Herschel Space Observatory, they used Webb to determine that each of the massive protostars is already more than 20 times the mass of the Sun. Webb also revealed the bright outflows powered by each protostar. T he MeerKAT radio telescope is among South Africa’s largest scientific infrastructure projects. It comprises 64 dishes, each 13.5m in diameter, and is a precursor to the Square Kilometre Ar- ray (SKA) project. [South African Radio Astronomy Observatory] Even more challenging is finding low-mass protostars, still shrouded in cocoons of cosmic dust. Re- searchers compared Webb’s data with ALMA’s past observations to identify five likely low-mass proto- star candidates. The team also identified 88 features that appear to be shocked hydro- gen gas, where material being blasted out in jets from young stars impacts the surrounding gas cloud. Analysis of these features led to the discovery of a new star-forming cloud, distinct from the main Sagit- tarius C cloud, hosting at least two protostars powering their own jets. “Outflows from forming stars in !