The Core Population and Kinematics of a Massive Clump at Early Stages: An Atacama Large Millimeter/submillimeter Array View

Abstract

Abstract High-mass star formation theories make distinct predictions on the properties of the prestellar seeds of high-mass stars. Observations of the early stages of high-mass star formation can provide crucial constraints, but they are challenging and scarce. We investigate the properties of the prestellar core population embedded in the high-mass clump AGAL014.492-00.139, and we study the kinematics at the clump and clump-to-core scales. We have analyzed an extensive data set acquired with the Atacama Large Millimeter/submillimeter Array interferometer. Applying a dendrogram analysis to the Band 7 o‐H2D+ data, we identified 22 cores. We fitted their average spectra in local thermodinamic equilibrium conditions, and we analyzed their continuum emission at 0.8 mm. The cores have transonic to mildly supersonic turbulence levels and appear to be mostly low-mass, with M core < 30 M ⊙ . Furthermore, we have analyzed Band 3 observations of the N2H+ (1–0) transition, which traces the large-scale gas kinematics. Using a friend-of-friend algorithm, we identify four main velocity coherent structures, all of which are associated with prestellar and protostellar cores. One of them presents a filament-like structure, and our observations could be consistent with mass accretion toward one of the protostars. In this case, we estimate a mass accretion rate of M ̇ acc ≈ 2 × 10 − 4 M ⊙ yr − 1 . Our results support a clump-fed accretion scenario in the target source. The cores in the prestellar stage are essentially low-mass, and they appear to be subvirial and gravitationally bound, unless further support is available, for instance, due to magnetic fields.