Speaker
Description
Understanding the physical and dynamical conditions of massive star-forming cores is essential for constraining how high-mass stars assemble their mass and shape their environments. G358.46−0.39 is a massive proto-cluster previously identified to host 4 cores (MM1a, MM1b, MM1c, and MM2), yet its internal gas structure, chemical complexity, and driving sources of outflow activity remain poorly characterized. To provide a clearer picture of its protostellar nature, we analyzed ALMA Band 7 archival data to investigate the spatial distribution of key molecular tracers – C¹⁷O, SiO, HC₃N and SO₂, as well as to quantify the energetics of associated outflows. The integrated C¹⁷O map reveals filamentary and dumbbell-like structures that likely represent gas compressed by the expansion of the H II region around MM2, offering new insight into the large-scale gas morphology. SiO emission uncovers spatially overlapping blue- and red-shifted lobes, consistent with a bipolar outflow driven by an unresolved young stellar object in MM1a. In contrast, HC₃N and SO₂ emission is confined exclusively to MM1a, where both species display compact structures. The SO₂ emission shows a distinct velocity gradient and large velocity dispersion (~ 3 kms⁻¹), indicating the presence of rotating and dynamically active material. We derived the mass, momentum, energy and associated rates of outflows and found that the SiO outflow morphology differs from the previously reported ¹²CO outflow. These differences suggest that the SiO and ¹²CO outflows originate from separate protostellar disks – one likely face-on and the other edge-on, pointing to multiplicity within MM1a. This work provides new evidence that MM1a hosts a massive, actively accreting protostar surrounded by complex gas motions and multiple outflow structures.
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