An ALMA Study of Molecular Complexity in the Hot Core G336.99-00.03 MM1

Abstract High-mass star formation involves complex processes, with the hot core phase playing a crucial role in chemical enrichment and the formation of complex organic molecules. However, molecular inventories in hot cores remain limited. Using data from the Atacama Large Millimeter/submillimeter Array Three-millimeter Observations of Massive Star-forming regions survey, the molecular composition and evolutionary stages of two distinct millimeter continuum sources in the high-mass star-forming region G336.99-00.03 have been characterized. MM1, with 19 distinct molecular species detected, along with eight isotopologues and several vibrationally/torsionally excited states, has been identified as a hot core. MM2, with only five species identified, was defined as a H ii region. Isotopic ratios in MM1 were derived, with 12 C/ 13 C ranging from 16.0 to 29.2, 16 O/ 18 O at 47.7, and 32 S/ 34 S at 19.2. Molecular abundances in MM1 show strong agreement with other sources and three-phase warm-up chemical models within an order of magnitude for most species. Formation pathways of key molecules were explored, revealing chemical links and reaction networks. This study provides a detailed molecular inventory of two millimeter continuum sources, shedding light on the chemical diversity and evolutionary processes in high-mass star-forming regions. The derived molecular parameters and isotopic ratios offer benchmarks for astrochemical models, paving the way for further investigation into the formation and evolution of complex organic molecules during the hot core phase.