The ALMA-QUARKS survey: Hot Molecular Cores are a long-standing phenomenon in the evolution of massive protostars

Dezhao Meng; Tie Liu; Jarken Esimbek; Sheng-Li Qin; Guido Garay; Paul F. Goldsmith; Jianjun Zhou; Xindi Tang; Wenyu Jiao; Yan-Kun Zhang; Fengwei Xu; Siju Zhang; Anandmayee Tej; Leonardo Bronfman; Aiyuan Yang; Sami Dib; Swagat R. Das; Jihye Hwang; Archana Soam; Yisheng Qiu; Dalei Li; Yuxin He; Gang Wu; Lokesh Dewangan; James O. Chibueze; Pablo García; Prasanta Gorai; Naval Kishor Bhadari; Yong Zhang; Patricio Sanhueza; Yongquan Luo; Jia-Hang Zou; Kee-Tae Kim; Dongting Yang; Lei Zhu; Xunchuan Liu; Macleod Gordon

arXiv · 2511.01285

The ALMA-QUARKS survey: Hot Molecular Cores are a long-standing phenomenon in the evolution of massive protostars

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Abstract

We present an analysis of the QUARKS survey sample, focusing on protoclusters where Hot Molecular Cores (HMCs, traced by CH3CN(12--11)) and UC HII regions (traced by H30\alpha/H40\alpha) coexist. Using the high-resolution, high-sensitivity 1.3 mm data from the QUARKS survey, we identify 125 Hot Molecular Fragments (HMFs), which represent the substructures of HMCs at higher resolution. From line integrated intensity maps of CH3CN(12--11) and H30\alpha, we resolve the spatial distribution of HMFs and UC HII regions. By combining with observations of CO outflows and 1.3 mm continuum, we classify HMFs into four types: HMFs associated with jet-like outflow, with wide-angle outflow, with non-detectable outflow, and shell-like HMFs near UC HII regions. This diversity possibly indicates that the hot core could be polymorphic and long-standing phenomenon in the evolution of massive protostars. The separation between HMFs and H30\alpha/H40\alpha emission suggests that sequential high-mass star formation within young protoclusters is not likely related to feedback mechanisms.

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Dezhao Meng, Tie Liu, Jarken Esimbek, Sheng-Li Qin, Guido Garay, Paul F. Goldsmith, Jianjun Zhou, Xindi Tang, Wenyu Jiao, Yan-Kun Zhang, Fengwei Xu, Siju Zhang, Anandmayee Tej, Leonardo Bronfman, Aiyuan Yang, Sami Dib, Swagat R. Das, Jihye Hwang, Archana Soam, Yisheng Qiu, Dalei Li, Yuxin He, Gang Wu, Lokesh Dewangan, James O. Chibueze, Pablo García, Prasanta Gorai, Naval Kishor Bhadari, Yong Zhang, Patricio Sanhueza, Yongquan Luo, Jia-Hang Zou, Kee-Tae Kim, Dongting Yang, Lei Zhu, Xunchuan Liu, Macleod Gordon. 2025-11-03. The ALMA-QUARKS survey: Hot Molecular Cores are a long-standing phenomenon in the evolution of massive protostars. https://arxiv.org/abs/2511.01285

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