分类： 天文学 >> 天文学 提交时间： 2023-02-19
Hong-Li Liu
Tie Liu
Neal J. Evans
Ke Wang
Guido Garay
Sheng-Li Qin
Shanghuo Li
Amelia Stutz
Paul F. Goldsmith
Sheng-Yuan Liu
Anandmayee Tej
Qizhou Zhang
Mika Juvela
Di Li
Jun-Zhi Wang
Leonardo Bronfman
Zhiyuan Ren
Yue-Fang Wu
Kee-Tae Kim
Chang-Won Lee
摘要： We have identified 453 compact dense cores in 3 mm continuum emission maps in the ATOMS (ALMA Three-millimeter Observations of Massive Star-forming regions) survey, and compiled three catalogues of high-mass star forming cores. One catalogue, referred to as H/UC-HII catalogue, includes 89 cores that enshroud hyper/ultra compact (H/UC) HII regions as characterized by associated compact H40alpha emission. A second catalogue, referred to as pure s-cHMC, includes 32 candidate Hot Molecular Cores (HMCs) showing rich spectra (N>20lines) of complex organic molecules (COMs) but not associated with H/UC-HII regions. The third catalogue, referred to as pure w-cHMC, includes 58 candidate HMCs with relatively low levels of COM richness and not associated with H/UC-HII regions. These three catalogues of dense cores provide an important foundation for future studies of the early stages of high-mass star formation across the Milky Way. We also find that nearly half of H/UC-HII cores are candidate HMCs. From the number counts of COM-containing and H/UC-HII cores, we suggest that the duration of high-mass protostellar cores showing chemically rich features is at least comparable to the lifetime of H/UC-HII regions. For cores in the H/UC-HII catalogue, the width of the H40alpha line increases as the core size decreases, suggesting that the non-thermal dynamical and/or pressure line-broadening mechanisms dominate on the smaller scales of the H/UC-HII cores.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Hong-Li Liu
Anandmayee Tej
Tie Liu
Namitha Issac
Anindya Saha
Paul F. Goldsmith
Jun-Zhi Wang
Qizhou Zhang
Sheng-Li Qin
Ke Wang
Shanghuo Li
Archana Soam
Lokesh Dewangan
Chang Won Lee
Pak-Shing Li
Xun-Chuan Liu
Yong Zhang
Zhiyuan Ren
Mika Juvela
Leonardo Bronfman
摘要： We present new 3-mm continuum and molecular lines observations from the ATOMS survey towards the massive protostellar clump, MM1, located in the filamentary infrared dark cloud (IRDC), G034.43+00.24 (G34). The lines observed are the tracers of either dense gas (e.g. HCO+/H13CO+ J = 1-0) or outflows (e.g. CS J = 2-1). The most complete picture to date of seven cores in MM1 is revealed by dust continuum emission. These cores are found to be gravitationally bound, with virial parameter, $\alpha_{vir}<2$. At least four outflows are identified in MM1 with a total outflowing mass of $\sim 45 M_\odot$, and a total energy of $\sim 1\times 10^{47}$ erg, typical of outflows from a B0-type star. Evidence of hierarchical fragmentation, where turbulence dominates over thermal pressure, is observed at both the cloud and the clump scales. This could be linked to the scale-dependent, dynamical mass inflow/accretion on clump and core scales. We therefore suggest that the G34 cloud could be undergoing a dynamical mass inflow/accretion process linked to the multiscale fragmentation, which leads to the sequential formation of fragments of the initial cloud, clumps, and ultimately dense cores, the sites of star formation.
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