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arXiv 0810.0875astro-ph
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大质量恒星形成核向内运动的多跃迁分子线研究

A multi-transition molecular line study of inward motions towards massive star-forming cores

Yan Sun, Yu Gao

摘要:

对29个大质量恒星形成核进行了多跃迁3 $ $ mm分子线单点和成图巡天,以寻找向内运动的特征。对每个源观察到多达七种不同的跃迁,光学粗线HCO $^+$(1-0)、CS(2-1)、HNC(1 - 0)、HCN(1-0)、$^{12}$ CO(1-0)和光学细线C $^{18}$ O(1-0)、$^{13}$ CO(1-0)。导出了每种源的光学粗线和光学细线C $^{18}$ O(1-0)峰值速度之间的归一化速度差($δ$ V $_{\rm CS}$,$δ$ V $_{\rm HCO^{+}}$)。在大多数源的HCO $^+$(1-0)或CS(2-1)或HNC(1-0)观测中可能存在显著的向内运动。我们的观察结果表明,CS(2-1)和HCO $^+$(1-0)之间的蓝移线不对称谱线发生率有显著差异。HCO $^+$(1-0)显示出最高的明显不对称特征,这可能是由于CS(2-1)和HCO $^+$(1-0)之间的光学深度不同。HCO $^+$(1-0)似乎是最好的向内运动示踪剂。多谱线转换的映射观测使我们能够识别出六个强入轨候选者G123.07-6.31,W75(OH),S235 N,CEP-A,W3(OH),NGC 7538。下落签名被扩展到线性尺度$>0.2 \:$ pc。

英文摘要:

A multi-transition 3$ $mm molecular line single-pointing and mapping survey was carried out towards 29 massive star-forming cores in order to search for the signature of inward motions. Up to seven different transitions, optically thick lines HCO$^+$(1-0), CS(2-1), HNC(1-0), HCN(1-0), $^{12}$CO(1-0) and optically thin lines C$^{18}$O(1-0), $^{13}$CO(1-0) were observed towards each source. The normalized velocity differences ($δ$V$_{\rm CS}$, $δ$V$_{\rm HCO^{+}}$) between the peak velocities of optically thick lines and optically thin line C$^{18}$O(1-0) for each source were derived. Prominent inward motions are probably present in either HCO$^+$(1-0) or CS(2-1) or HNC(1-0) observations in most sources. Our observations show that there is a significant difference in the incidence of blue shifted line asymmetric line profiles between CS(2-1) and HCO$^+$(1-0). The HCO$^+$(1-0) shows the highest occurrence of obvious asymmetric feature, perhaps owing to different optical depth between CS(2-1) and HCO$^+$(1-0). HCO$^+$(1-0) appears to be the best inward motion tracer. The mapping observations of multiple line transitions enable us to identify six strong infall candidates G123.07-6.31, W75(OH), S235N, CEP-A, W3(OH), NGC7538. The infall signature is extended up to a linear scale $>0.2 \:$pc.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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