Molecular analysis of a high-mass prestellar core candidate in W43-MM1

Abstract

High-mass analogues of low-mass prestellar cores are searched for to constrain the models of high-mass star formation. Several high-mass cores, at various evolutionary stages, have been recently identified towards the massive star-forming region W43-MM1 and amongst them a high-mass prestellar core candidate. We aim to characterise the chemistry in this high-mass prestellar core candidate, referred to as W43-MM1 core #6, and its environment. Using ALMA high-spatial resolution data of W43-MM1, we have studied the molecular content of core #6 and a neighbouring high-mass protostellar core, referred to as #3, which is similar in size and mass to core #6. We first subtracted the continuum emission using a method based on the density distribution of the intensities on each pixel. Then, from the distribution of detected molecules, we identified the molecules centred on the prestellar core candidate (core #6) and those associated to shocks related to outflows and filament formation. Then we constrained the column densities and temperatures of the molecules detected towards the two cores. While core #3 appears to contain a hot core with a temperature of about 190 K, core #6 seems to have a lower temperature in the range from 20 K to 90 K from a rotational diagram analysis. We have considered different source sizes for core #6 and the comparison of the abundances of the detected molecules towards the core with various interstellar sources shows that it is compatible with a core of size 1000 au with $T=20-90$ K or a core of size 500 au with $T\sim 80$ K. Core #6 of W43-MM1 remains one of the best high-mass prestellar core candidates even if we cannot exclude that it is at the very beginning of the protostellar phase of high-mass star formation.

18 pages, 8 figures, Accepted for publication in Astronomy & Astrophysics

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• ALMA-IMF. V. Prestellar and protostellar core populations in the W43 cloud complex
• N-bearing complex organics toward high-mass protostars: Constant ratios pointing to formation in similar pre-stellar conditions across a large mass range
• ATOMS: ALMA Three-millimeter Observations of Massive Star-forming regions -- VIII. A search for hot cores by using C${}_2$H${}_5$CN, CH${}_3$OCHO and CH${}_3$OH lines
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• A global view on star formation: The GLOSTAR Galactic plane survey III. 6.7 GHz methanol maser survey in Cygnus X
• ALMA-IMF. VII. First release of the full spectral line cubes: Core kinematics traced by DCN J=(3-2)
• An ALMA study of the massive molecular clump N159W-North in the Large Magellanic Cloud: A possible gas flow penetrating one of the most massive protocluster systems in the Local Group
• ALMA-IMF IV -- A comparative study of the main hot cores in W43-MM1: detection, temperature and molecular composition
• ALMA-IMF XVI: Mass-averaged temperature of cores and protostellar luminosities in the ALMA-IMF protoclusters
• ALMA-IMF XVII -- Census and lifetime of high-mass prestellar cores in 14 massive protoclusters
• Core to ultracompact HII region evolution in the W49A massive protocluster
• Unveiling the substructure of the massive clump AGAL G035.1330$-$00.7450
• ATOMS: ALMA Three-millimeter Observations of Massive Star-forming regions -- X. Chemical differentiation among the massive cores in G9.62+0.19
• Sub-arcsecond Imaging of the Complex Organic Chemistry in Massive Star-forming Region G10.6-0.4