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Abstract We present JWST-NIRCam narrowband, 4.05μm Brαimages of the Sgr C Hiiregion, located in the central molecular zone (CMZ) of the Galaxy. Unlike any Hiiregion in the solar vicinity, the Sgr C plasma is dominated by filamentary structure in both Brαand the radio continuum. Some bright filaments, which form a fractured arc with a radius of about 1.85 pc centered on the Sgr C star-forming molecular clump, likely trace ionization fronts. The brightest filaments form a “π-shaped” structure in the center of the Hiiregion. Fainter filaments radiate away from the surface of the Sgr C molecular cloud. The filaments are emitting optically thin free–free emission, as revealed by spectral index measurements from 1.28 GHz (MeerKAT) to 97 GHz (Atacama Large Millimeter/submillimeter Array). But, the negative in-band 1 to 2 GHz spectral index in the MeerKAT data alone reveals the presence of a nonthermal component across the entire Sgr C Hiiregion. We argue that the plasma flow in Sgr C is controlled by magnetic fields, which confine the plasma to ropelike filaments or sheets. This results in the measured nonthermal component of low-frequency radio emission plasma, as well as a plasmaβ(thermal pressure divided by magnetic pressure) below 1, even in the densest regions. We speculate that all mature Hiiregions in the CMZ, and galactic nuclei in general, evolve in a magnetically dominated, low plasmaβregime. 

Abstract We present James Webb Space Telescope (JWST) Near Infrared Camera observations of the massive star-forming molecular cloud Sagittarius C (Sgr C) in the Central Molecular Zone (CMZ). In conjunction with ancillary mid-IR and far-IR data, we characterize the two most massive protostars in Sgr C via spectral energy distribution (SED) fitting, estimating that they each have current masses ofm_*∼ 20M_⊙and surrounding envelope masses of ∼100M_⊙. We report a census of lower-mass protostars in Sgr C via a search for infrared counterparts to millimeter continuum dust cores found with the Atacama Large Millimeter/submillimeter Array (ALMA). We identify 88 molecular hydrogen outflow knot candidates originating from outflows from protostars in Sgr C, the first such unambiguous detections in the infrared in the CMZ. About a quarter of these are associated with flows from the two massive protostars in Sgr C; these extend for over 1 pc and are associated with outflows detected in ALMA SiO line data. An additional ∼40 features likely trace shocks in outflows powered by lower-mass protostars throughout the cloud. We report the discovery of a new star-forming region hosting two prominent bow shocks and several other line-emitting features driven by at least two protostars. We infer that one of these is forming a high-mass star given an SED-derived mass ofm_*∼ 9M_⊙and associated massive (∼90M_⊙) millimeter core and water maser. Finally, we identify a population of miscellaneous molecular hydrogen objects that do not appear to be associated with protostellar outflows. 

Abstract We present ∼8–40μm SOFIA-FORCAST images of seven regions of “clustered” star formation as part of the SOFIA Massive Star Formation Survey. We identify a total of 34 protostar candidates and build their spectral energy distributions (SEDs). We fit these SEDs with a grid of radiative transfer models based on the turbulent core accretion (TCA) theory to derive key protostellar properties, including initial core mass,M_c, clump environment mass surface density, Σ_cl, and current protostellar mass,m_*. We also carry out empirical graybody (GB) estimation of Σ_cl, which allows a case of restricted SED fitting within the TCA model grid. We also release version 2.0 of the open-source Python packagesedcreator, which is designed to automate the aperture photometry and SED building and fitting process for sources in clustered environments, where flux contamination from close neighbors typically complicates the process. Using these updated methods, SED fitting yields values ofM_c∼ 30–200M_⊙, Σ_cl,SED∼ 0.1–3 g cm⁻², andm_*∼ 4–50M_⊙. The GB fitting yields smaller values of Σ_cl,GB≲ 1 g cm⁻². From these results, we do not find evidence for a critical Σ_clneeded to form massive (≳8M_⊙) stars. However, we do find tentative evidence for a dearth of the most massive (m_*≳ 30M_⊙) protostars in the clustered regions, suggesting a potential impact of environment on the stellar initial mass function.