Structure of the Dense Molecular Gas in the NGC 1333 IRAS 4 Region
Structure of the Dense Molecular Gas in the NGC 1333 IRAS 4 Region
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NGC 1333 IRAS 4 区域中稠密分子气体的结构
DOI：
10.1086/425898
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
J. Panis
中科院分区：
文献类型：
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作者：
Minho Choi;T. Kamazaki;K. Tatematsu;J. Panis
用单盘望远镜在Hcn和Hco+J=1→0谱线上观察到了NGC1333IRAS4区，用干涉仪在2.1 mm连续谱和H_2CO J=2 1→111线上观察到了NGC1333IRAS 4区.单碟图显示，辐射中至少存在两个速度分量：一个是与IRAS4核有关的VLSR=6.7 km S-1，另一个是与从SVS13复合体延伸而来的云有关的~8 km S-1。此外，在约8公里的S-1上有一个前景冷层，导致大部分测区被吸收。云层结构表明，IRAS 4A/B的蓝色偏斜线轮廓可能不是原恒星崩塌的迹象。对单盘和干涉图的检验表明，以前在干涉光谱中看到的IRAS 4A/B的下沉可能主要是由大尺度前景层造成的，部分是由于缺少短间距通量。不能排除被具有不寻常速度分布的流入包络吸收的可能性。HCO+图谱揭示了其他分子核心，一个与SK 1有关，另一个与SK 10/14有关。它们可能是恒星形成的地点。
The NGC 1333 IRAS 4 region was observed in the HCN and HCO+ J = 1 → 0 lines using a single-dish telescope and in the 2.1 mm continuum and the H2CO J = 212 → 111 line using an interferometer. The single-dish maps show that there are at least two velocity components in emission: one at VLSR = 6.7 km s-1 associated with the IRAS 4 core, and the other at ~8 km s-1 associated with a cloud extended from the SVS 13 complex. In addition, there is a foreground cold layer at ~8 km s-1 that causes absorption over most of the mapped area. The cloud structure suggests that the blue-skewed line profile of IRAS 4A/B may not be a sign of protostellar collapse. Examinations of both single-dish and interferometric maps suggest that the dip previously seen in the interferometric spectra toward IRAS 4A/B may be caused mostly by the large-scale foreground layer and partly by missing short-spacing flux. Absorption by an infalling envelope with an unusual velocity profile cannot be ruled out. The HCO+ map revealed other molecular cores, one associated with SK 1, and the other with SK 10/14. They are probable sites of star formation.