星际介质PDR和XDR结构的微波谱线诊断

发布时间：2018-01-01 02:18

本文关键词：星际介质PDR和XDR结构的微波谱线诊断　出处：《天文学进展》2013年02期 　论文类型：期刊论文

【摘要】：星际介质(ISM)的物理性质和化学平衡受多种加热和冷却过程的影响。光子主导区(PDR)和X射线主导区(XDR)是恒星形成过程中星际介质的两个主要结构。PDR和XDR区的主导能源机制不同,造成星际介质的物理性质和化学成分上有很大不同,反映在不同种类分子、同种分子不同跃迁能级之间以及分子同位素之间的谱线强度比有显著差异,因此可以利用分子谱线强度比作为区分PDR和XDR的示踪工具。PDR和XDR模型的数值模拟表明,分子谱线中HNC/HCN、HCN/HCO+以及HCN/CO谱线强度比可以有效地区分PDR区和XDR区。此外,CN/HCN、NO/CO以及HOC+/HCO+的柱密度比值也可以指示PDR和XDR区。PDR和XDR的微波分子谱线诊断技术已经应用在河外星系的物理和化学演化研究中,不仅证实了该技术的有效性,而且在PDR和XDR模型中引入机械能反馈机制后,使得模型能够更贴切地符合观测结果,为理解河外星系的演化打开了一扇新的窗口。
[Abstract]:The physical properties and chemical equilibrium of the interstellar medium ISM are affected by a variety of heating and cooling processes. Photonic dominant region (PDR) and X-Ray dominant region (XDRR). PDR is the two main structure of interstellar media during star formation. PDR is different from the dominant energy mechanism in XDR region. The physical properties and chemical composition of interstellar media are very different, which is reflected in the significant differences in spectral intensity ratios between different kinds of molecules, different transition energy levels of the same molecule and molecular isotopes. Therefore, the molecular spectral line intensity ratio can be used as a tracer for distinguishing PDR from XDR. The numerical simulation of PDR and XDR model shows that the HNC/HCN in the molecular spectral line can be used as a tracer. HCN/HCO and HCN/CO line intensity ratio can effectively distinguish the PDR region from the XDR region. NO/CO and HOC / HCO. The column density ratio can also indicate that the microwave molecular line diagnostics of PDR and XDR regions. PDR and XDR have been applied in the physical and chemical evolution of the extragalactic system. Not only the effectiveness of the technique is verified, but also the mechanical energy feedback mechanism is introduced into the PDR and XDR models, which makes the model more appropriate to the observed results. A new window is opened to understand the evolution of the extragalactic system.
【作者单位】：中国科学院上海天文台;中国科学院大学;中国科学院射电天文重点实验室;
【基金】：973项目(2013CB837900) 中国科学院空间科学战略性先导科技专项(XDA04060700)
【分类号】：P152
【正文快照】： 1引言星际介质(interstellar-medium,简称ISM)是对恒星际空间气体、尘埃微粒、磁场,以及作相对论性运动的电子、质子和其他原子核的统称。气体和尘埃是星际介质的主要成分,是星系中重要的重子物质,也是形成恒星的原料。银河系中大约有1000亿颗恒星,质量从0.1 M到100 M大小不等

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