Dust Motions in Magnetized Turbulence: Source of Chemical Complexity
Dust Motions in Magnetized Turbulence: Source of Chemical Complexity
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DOI：
10.3847/2041-8213/aae529
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发表时间：
2018-10-20
影响因子：
7.9
通讯作者：
Cecchi-Pestellini, Cesare
中科院分区：
文献类型：
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作者：
Cassone, Giuseppe;Saija, Franz;Cecchi-Pestellini, Cesare
除了通过撞击彗星和冰冷行星表面的类似物制造复杂的有机分子（这是公认的）之外，由星际或星际区域的湍流驱动的尘埃颗粒与颗粒的碰撞可能代表了一条平行的化学途径，用于生命起源相关物种的冲击合成。在这里，我们报告了一项基于多尺度冲击压缩技术与从头算分子动力学方法相结合的研究，其中包含冰颗粒的相互碰撞异氰酸（HNCO）的冲击波驱动的化学反应已通过第一原理进行了模拟。在触发样品化学转变的冲击波速度阈值（7 km s(-1)）下，甲酰胺是第一个合成的物质，因此是系统进一步复杂化的跳板。而且，随着冲击速度的增加，甲酰胺的形成量逐渐增大。更有趣的是，在考虑的最高速度（10 km s(-1)）下，影响会驱动多种碳-碳键物种的产生。除了甘氨酸之外，在对含有宇宙中最广泛的分子 (H-2) 和含有所有主要生物元素的最简单化合物 (HNCO) 的样品进行冲击压缩后，还检测到了丙氨酸（即乙胺胺）的组成部分和多种氨基酸的主要成分之一，包括天冬酰胺、半胱氨酸和亮氨酸（即乙烯胺）。目前的结果表明了实现星际和星际区域典型化学复杂性的新化学途径。
In addition to the manufacture of complex organic molecules from impacting cometary and icy planet surface analogs, which is well-established, dust grain-grain collisions driven by turbulence in interstellar or circumstellar regions may represent a parallel chemical route toward the shock synthesis of prebiotically relevant species. Here we report on a study, based on the multi-scale shock-compression technique combined with ab initio molecular dynamics approaches, where the shock-wave-driven chemistry of mutually colliding isocyanic acid (HNCO) containing icy grains has been simulated by first principles. At the shock-wave velocity threshold triggering the chemical transformation of the sample (7 km s(-1)), formamide is the first synthesized species, thus being the springboard for the further complexification of the system. Also, upon increasing the shock impact velocity, formamide is formed in progressively larger amounts. More interestingly, at the highest velocity considered (10 km s(-1)), impacts drive the production of diverse carbon-carbon bonded species. In addition to glycine, the building block of alanine (i.e., ethanimine) and one of the major components of a plethora of amino acids including, e.g., asparagine, cysteine, and leucine (i.e., vinylamine), have been detected after shock compression of samples containing the most widespread molecule in the universe (H-2) and the simplest compound bearing all of the primary biogenic elements (HNCO). The present results indicate novel chemical pathways toward the chemical complexity typical of interstellar and circumstellar regions.