AFGL 2343：29 SiO和HCN高激发区示踪剂的质量壳层结构和化学
The structure and chemistry of the massive shell around AFGL 2343: 29SiO and HCN as tracers of high-excitation regions
摘要：
黄色超巨星（YHG）是非常巨大的天体，预计在其演化过程中会经历强烈的质量损失时期。尽管如此，大质量的拱星包层只在其中两个中发现，IRC+10420和AFGL 2343。这些物体周围的包层和形成它们的过程知之甚少。我们的目标是研究AFGL 2343周围的结构，动力学和化学。我们得到了29 SiOJ = 2-1，HCNJ = 1-0和SOJ（K）= 2（2）-1（1）的干涉图。我们用LVG激发模型分析了AFGL 2343的新观测和一些先前发表的谱线轮廓。对观测数据的分析和拟合结果表明，在先前确定的CO壳层中存在一个薄的、热的和致密的成分。这一成分可能与最近受到冲击的气体有关，但也可能是由于一个阶段的大量质量损失。我们认为，这个壳层是负责整个29 SiO的排放和显着贡献的HCN排放。这种富含SiO的致密壳层的存在可能与以前在IRC+10420中发现的有关，这也被认为是由冲击造成的。这可能是这些恒星演化过程中的一个共同特征，因为它们在演化过程中经历了偶发的质量损失期。我们提出了新的结果的质量损失模式，拱星包络的总质量和分子丰度的一些物种在AFGL 2343。
英文摘要：
The yellow hypergiant stars (YHGs) are very massive objects that are expected to pass through periods of intense mass loss during their evolution. Despite of this, massive circumstellar envelopes have been found only in two of them, IRC+10420 and AFGL 2343. The envelopes around these objects and the processes that form them are poorly known. We aim to study the structure, dynamics and chemistry of the envelope around AFGL 2343. We have obtained interferometric maps of the rotational lines 29SiO J= 2-1, HCN J= 1-0 and SO J(K)= 2(2)-1(1) towards AFGL 2343. We have used an LVG excitation model to analyze the new observations and some previously published line profiles of AFGL 2343. The analysis of the observational data and the fitting results show the presence of a thin, hot and dense component within the previously identified CO shell. This component can be associated with recently shocked gas, but it could also be due to a phase of extremely copious mass loss. We suggest that this shell is the responsible for the whole 29SiO emission and significantly contributes to the HCN emission. The presence of such a dense shell rich in SiO can be related with that previously found for IRC+10420, which was also suggested to result from a shock. This may be a common feature in the evolution of these stars, as a consequence of the episodic mass loss periods that they pass during their evolution. We present new results for the mass loss pattern, the total mass of the circumstellar envelope and the molecular abundances of some species in AFGL 2343.
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。
