Low-temperature synthesis of polycyclic aromatic hydrocarbons in Titan's surface ices and on airless bodies
Low-temperature synthesis of polycyclic aromatic hydrocarbons in Titan's surface ices and on airless bodies
复制标题
DOI：
10.1126/sciadv.aaw5841
复制
发表时间：
2019-10-01
期刊：
影响因子：
13.6
通讯作者：
Kaiser, Ralf I.
中科院分区：
文献类型：
--
作者：
Abplanalp, Matthew J.;Frigge, Robert;Kaiser, Ralf I.
泰坦的赤道沙丘代表了我们太阳系中最具纪念意义的表面结构，但其黑暗有机物的化学成分仍然是一个基本的未解之谜，在沙丘附近检测到的固体乙炔被认为是一种关键原料。在这里，我们在实验室模拟实验中揭示，苯、萘和菲等芳香族化合物（有机沙丘材料的潜在组成部分）可以通过泰坦表面低温乙炔冰的银河宇宙射线暴露有效合成，因此挑战了传统观点认为芳香族碳氢化合物仅在泰坦大气中形成。这些过程对于揭示外太阳系中无空气天体的黑暗表面的起源和化学成分也至关重要，因为那里的大气中不会发生碳氢化合物沉淀。这一发现显著地推进了我们对整个太阳系中碳分布的理解，例如在像鸟神星这样的柯伊伯带天体上。
Titan's equatorial dunes represent the most monumental surface structures in our Solar System, but the chemical composition of their dark organics remains a fundamental, unsolved enigma, with solid acetylene detected near the dunes implicated as a key feedstock. Here, we reveal in laboratory simulation experiments that aromatics such as benzene, naphthalene, and phenanthrene-prospective building blocks of the organic dune material-can be efficiently synthesized via galactic cosmic ray exposure of low-temperature acetylene ices on Titan's surface, hence challenging conventional wisdom that aromatic hydrocarbons are formed solely in Titan's atmosphere. These processes are also of critical importance in unraveling the origin and chemical composition of the dark surfaces of airless bodies in the outer Solar System, where hydrocarbon precipitation from the atmosphere cannot occur. This finding notably advances our understanding of the distribution of carbon throughout our Solar System such as on Kuiper belt objects like Makemake.