arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2007.14362astro-ph.GA
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作为银河系中心分子云化学复杂性驱动因素的云-云碰撞

Cloud-cloud collision as drivers of the chemical complexity in Galactic Centre molecular clouds

S. Zeng, Q. Zhang, I. Jimenez-Serra, B. Tercero, X. Lu, J. Martin-Pintado, P. de Vicente, V. M. Rivilla, S. Li

摘要:

G+0.693-0.03是一个静止的分子云,位于人马座B2(Sgr B2)恒星形成复合体内。最近的光谱调查表明,它是银河系中复杂有机物种最丰富的储藏库之一。这种化学复杂性的起源,以及G+0.693-0.03的小尺度物理结构和性质,仍然是一个谜。在本文中,我们报告的多分子的研究与干涉观测相结合的单盘数据在G+0.693-0.03。尽管缺乏连续源的检测,我们发现小规模(0.2 pc)的结构在这个云。典型的冲击示踪剂,如SiO,HNCO和CH $_3$ OH的分子发射的分析揭示了两个分子成分,峰值速度为57和75公里秒$^{-1}$。它们在空间和速度上都是相互联系的。位置-速度图显示了与云-云碰撞的观测特征相匹配的特征。此外,我们检测到三个系列的类\rom{1}甲醇脉泽已知出现在冲击气体,支持云云碰撞的情况。从脉泽发射,我们提供的气体动力学温度($\sim$ 30-150 K)和H $_2$密度(10 $^4$-10 $^5$ cm $^{-2}$)的限制。这些特性与同样使用\rom{1}类甲醇脉泽发现的星爆星系NGC 253相似,被认为与云-云碰撞有关。我们的结论是,由可能的云-云碰撞驱动的冲击可能是G+0.693-0.03中观察到的高水平化学复杂性的最重要的机制。

英文摘要:

G+0.693-0.03 is a quiescent molecular cloud located within the Sagittarius B2 (Sgr B2) star-forming complex. Recent spectral surveys have shown that it represents one of the most prolific repositories of complex organic species in the Galaxy. The origin of such chemical complexity, along with the small-scale physical structure and properties of G+0.693-0.03, remains a mystery. In this paper, we report the study of multiple molecules with interferometric observations in combination with single-dish data in G+0.693-0.03. Despite the lack of detection of continuum source, we find small-scale (0.2 pc) structures within this cloud. The analysis of the molecular emission of typical shock tracers such as SiO, HNCO, and CH$_3$OH unveiled two molecular components, peaking at velocities of 57 and 75 km s$^{-1}$. They are found to be interconnected in both space and velocity. The position-velocity diagrams show features that match with the observational signatures of a cloud-cloud collision. Additionally, we detect three series of class \rom{1} methanol masers known to appear in shocked gas, supporting the cloud-cloud collision scenario. From the maser emission we provide constraints on the gas kinetic temperatures ($\sim$30-150 K) and H$_2$ densities (10$^4$-10$^5$ cm$^{-2}$). These properties are similar to those found for the starburst galaxy NGC253 also using class \rom{1} methanol masers, suggested to be associated with a cloud-cloud collision. We conclude that shocks driven by the possible cloud-cloud collision is likely the most important mechanism responsible for the high level of chemical complexity observed in G+0.693-0.03.

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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