The core population and kinematics of a massive clump at early stages: an ALMA view

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 the clump-to-core scales. We have analysed an extensive dataset acquired with the ALMA interferometer. Applying a dendrogram analysis to the Band o-${\mathrm{H}}_2{\mathrm{D}}^{+}$ data, we identified 22 cores. We have fitted their average spectra in local-thermodinamic-equilibrium conditions, and we analysed their continuum emission at $0.8\mathrm{mm}$. The cores have transonic to mildly supersonic turbulence levels and appear mostly low-mass, with $M_{\mathrm{core}}<30{\mathrm{M}}_{\odot }$. Furthermore, we have analysed Band 3 observations of the ${\mathrm{N}}_2{\mathrm{H}}^{+}$ (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 towards one of the protostars. In this case, we estimate a mass accretion rate of ${\dot{M}}_{\mathrm{acc}}\approx 2\times 10^{-4}{\mathrm{M}}_{\odot }\mathrm{y}{\mathrm{r}}^{-1}$. Our results support a clump-fed accretion scenario in the targeted source. The cores in prestellar stage are essentially low-mass, and they appear subvirial and gravitationally bound, unless further support is available for instance due to magnetic fields.

Accepted for publication in ApJ

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