Oral Presentation

From Irradiated Envelope to Star-forming Interior: A Multi-wavelength Polarimetric View of Sagittarius C

Author(s): Huixin Zhang (University College London), Kate Pattle (University College London), and Janik Karoly (University College London)

Presenter: Huixin Zhang (University College London)

Sagittarius C (Sgr C) is a strongly irradiated cloud in the Central Molecular Zone (CMZ) where external compression from a neighbouring H II region may coincide with very young massive star formation, making it a compelling site for examining the star formation in an extreme environment. This poster presents a multi-wavelength polarimetric study of Sgr C, combining JCMT B-fields in Star-forming Region Observations (BISTRO) 850 μm and SOFIA HAWC+ 214 μm observations to constrain the magnetic field and dust polarisation spectrum in a high-mass star-forming region. The results suggest that both the polarisation spectrum and the dynamical role of the magnetic field vary strongly with position. The 850 μm observations, tracing the bulk of the cloud, indicate that Sgr C is mildly magnetically supercritical overall, including in its brightest region, while more diffuse regions appear subcritical, suggesting that magnetic support remains dynamically important across the cloud. Comparisons with dust models indicate that emission from regions close to the H II interface cannot be reproduced by a single-temperature dust model, favouring a layered or line-of-sight mixed picture in which an externally heated envelope and a colder interior contribute differently at different wavelengths. We also discuss the broader implications of these results for understanding the role of magnetic fields in the CMZ star-forming environment.