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arXiv 2310.04045astro-ph.GA
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在大质量恒星形成区IRAS 16351-4722中发现的一个低质量富线核

A low-mass line-rich core found in Massive Star-forming Region IRAS 16351-4722

Meizhu Liu, Sheng-Li Qin, Tie Liu, Mengyao Tang, Sheng-Yuan Liu, Li Chen, ChuanShou Li, HongQiong Shi, Xiaohu Li, Tianwei Zhang, Ken'ichi Tatematsu, Fengwei Xu, Yuefang Wu

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22 pages, 5 figures, 5 tables, 70 references, accepted by ApJ
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AI总结：

本研究利用ALMA亚角秒分辨率观测，首次在大质量恒星形成区IRAS 16351-4722中同时发现一个具有热核特征的大质量富线核和一个低质量富线核，通过分子丰度对比验证了二者的性质差异。

摘要：

我们对大质量恒星形成区IRAS 16351-4722（以下简称I16351）开展了345 GHz频段的ALMA亚角秒分辨率连续谱与分子线观测。基于高空间分辨率连续谱观测，共探测到12个尘埃核。其中，一个大质量核（11.6倍太阳质量）和一个低质量核（1.7倍太阳质量）呈现出丰富的分子线发射。在大质量核和低质量核中，分别识别出来自29种分子的164条分子跃迁谱线，以及来自25种分子的104条分子跃迁谱线。两个核中均探测到CH3OH、CH3OCHO、CH3OCH3、C2H5OH、C2H5CN等复杂有机分子（COM）。在局部热动平衡（LTE）假设下，利用XCLASS软件推导了复杂有机分子的转动温度和柱密度。结果显示，低质量核和大质量核的最高转动温度分别约为130 K和198 K。此外，大质量核的谱线宽度大于低质量核。丰富的复杂有机分子跃迁谱线、较高的气体温度以及较窄的谱线宽度，首次表明该大质量恒星形成区中存在一个低质量富线核，而大质量富线核则表现出热核特征。通过将两个核中CH3OH、CH3OCHO、CH3OCH3和C2H5OH的分子丰度，与文献中报道的其他热核和热卡利诺（hot corino）进行对比，我们进一步证实I16351中同时探测到了一个热核和一个低质量富线核。

英文摘要：

We present ALMA sub-arcsecond-resolution observations of both continuum and molecular lines at 345 GHz towards the massive star-forming region IRAS 16351-4722 (hereafter I16351). A total of 12 dust cores were detected based on high spatial resolution observations of the continuum. Among them, a high-mass core (11.6 Msun) and a low-mass core (1.7 Msun) show abundant molecular line emissions. 164 molecular transitions from 29 species and 104 molecular transitions from 25 species are identified in the high-mass and low-mass cores, respectively. Complex organic molecules (COMs) such as CH3OH, CH3OCHO, CH3OCH3, C2H5OH, and C2H5CN are detected in the two cores. Under the assumption of local thermodynamic equilibrium (LTE), rotational temperatures and column densities of the COMs are derived with the XCLASS software. The maximum rotation temperature values in the low-mass core and the high-mass core were found to be approximately 130 K and 198 K, respectively. Additionally, the line widths in the high-mass core are larger than those in the low-mass one. Abundant complex organic molecular line transitions, high gas temperatures, and smaller line widths indicate the presence of a low-mass line-rich core in the massive star formation region for the first time, while the high-mass line-rich core shows hot core property. When comparing the molecular abundances of CH3OH, CH3OCHO, CH3OCH3 and C2H5OH of the two cores with other hot cores and hot corinos reported in the literature, we further confirm that both a hot core and a low-mass line-rich core are simultaneously detected in I16351.

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