Sagittarius C, a complex star-forming zone within a dense cloud ring near the Galactic Center, has long intrigued astronomers due to its tangle of gas filaments and intense stellar activity. A team led by Roy Zhao, a PhD student at the University of Chicago's Department of Physics and the Kavli Institute for Cosmological Physics, measured the region's magnetic field using infrared data from NASA's now-retired SOFIA airborne observatory. Their results were recently published in the Astrophysical Journal.
The research focused on how interstellar dust, aligned by magnetic fields, emits polarized infrared light. By capturing that light at a wavelength of 214 microns, the team mapped the magnetic field orientation within cold clouds of gas in Sgr C. The data reveal the field curves around a bubble of ionized gas likely formed by stellar winds from massive young stars-pushing and shaping both the surrounding gas and the field itself.
This expanding bubble appears to link directly with the origin of the Milky Way's radio filaments, thin structures first discovered in the 1980s by co-author and UCLA astrophysicist Prof. Mark Morris. The observed field geometry supports a leading theory: that reconnection of magnetic field lines near the bubble's edge accelerates electrons to near light speed, generating the filaments. This finding may apply to other filamentary structures throughout the Galactic Center.
The study also showed that magnetic fields significantly influence how cold gas, star-forming regions, and hot ionized zones interact-providing a blueprint for interpreting similar environments in other galaxies. The research team now plans follow-up observations using different wavelengths to explore hotter regions invisible to the current data.
Zhao noted that Sgr C has historically received less attention than nearby Sagittarius A*, the site of the Milky Way's central black hole. But its dynamic mix of gas, stars, and energetic particles makes it a uniquely revealing astrophysical case study.
One of the study's most surprising outcomes was the alignment between the newly measured magnetic field and prior data on ionized carbon emission in the same region. This agreement confirmed the bubble structure and pointed to a powerful Wolf-Rayet star as the likely source driving its expansion.
Related Links
Stratospheric Observatory for Infrared Astronomy
Stellar Chemistry, The Universe And All Within It
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