Unveiling the substructure of the massive clump AGAL G035.1330$-$00.7450 (2112.13735v1)

Abstract: It is known that massive stars form as result of the fragmentation of molecular clumps. However, what is not clear is whether this fragmentation gives rise to cores massive enough to form directly high-mass stars, or leads to cores of low and intermediate mass that generate massive stars acquiring material from their environment. Detailed studies towards clumps at early stages of star formation are needed to collect observational evidence that shed light on this issue. The infrared-quiet massive clump AGAL G035.1330-00.7450, located at a distance of 2.1 kpc, is a promising object to study both the fragmentation and the star formation activity at early stages. Using millimeter observations of continuum and molecular lines obtained from the Atacama Large Millimeter Array database at Bands 6 and 7, we study the substructure of this source. The angular resolution of the data at Band 7 is about 0\farcs7, which allow us to resolve structures of about 0.007 pc ($\sim$1500 au). We found that the clump harbours four dust cores (C1-C4) with masses below 3 M${\odot}$. Cores C3 and C4 exhibit well collimated, young, and low-mass molecular outflows. C1 and C2 present CH$_3$CN J=13--12 emission, from which we derive rotational temperatures of about 180 and 100 K, and masses of about 1.4 and 0.9 M${\odot}$, respectively. The moment 1 map of the CH$_3$CN emission suggests the presence of a rotating disk towards C1, which is confirmed by the CH$_3$OH and CH$_3$OCHO (20-19) emissions. On the other hand, CN N=2-1 emission shows a clumpy and filamentary structure that seems to connect all the cores. These filaments might be tracing the remnant gas of the fragmentation processes taking place within the clump, or gas that is being transported towards the cores, which would imply a competitive accretion scenario.