ALMA reveals an explosive outflow candidate in IRAS 16119−5048

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ABSTRACT We present a multiwavelength study of the massive star formation region IRAS 16119−5048 (I16119) using ALMA ATOMS Band 3 and QUARKS Band 6 observations, complemented by archival ATCA radio continuum and Spitzer mid-infrared data. The CO (2–1) emission reveals a system of high-velocity streamer-like structures around the central region. Using a dendrogram analysis of velocity-channel maps followed by linking in position–position–velocity space, we identify 16 streamers that are approximately radially distributed and whose projected trajectories converge toward a common central region. We found that the kinetic energy of the outflows is at least an order of magnitude lower than those of most known explosive outflows, but the mass entrainment rate and momentum rate are high compared with typical protostellar outflows, suggesting that I16119 may represent a low-energy explosive outflow candidate. Dense-gas and photodissociation-region tracers reveal shell-like structures associated with the 8 μm emission, indicating that feedback from the H ii region may influence the streamer morphology. The 1.3 mm continuum emission resolves 27 dense cores along a fragmented filamentary structure. Their separations are consistent with thermal Jeans or thermal cylindrical fragmentation, while the collect and collapse scenario is unsupported. The dense cores also show evidence of mass segregation, with the most massive cores concentrated near the inferred explosive centre. We therefore suggest that I16119 is a plausible low-energy explosive outflow candidate, possibly triggered by dynamical interactions among centrally concentrated massive cores. However, the complex velocity structure and possible contamination from individual core-driven outflows prevent a definitive classification. More sensitive, higher angular-resolution, and dedicated observations are required to confirm the nature of the outflow in this region.

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