Kuiper Belt objects exhibit a wider color range than any other solar system population. The origin of this color diversity is unknown, but likely the result of the prolonged irradiation of organic materials by galactic cosmic rays (GCRs). Here, we combine ultrahigh-vacuum irradiation experiments with comprehensive spectroscopic analyses to examine the color evolution during GCR processing methane and acetylene under Kuiper Belt conditions. This study replicates the colors of a population of Kuiper Belt objects such as Makemake, Orcus, and Salacia. Aromatic structural units carrying up to three rings as in phenanthrene (C 14 H 10 ), phenalene (C 9 H 10 ), and acenaphthylene (C 12 H 8 ), of which some carry structural motives of DNA and RNA connected via unsaturated linkers, were found to play a key role in producing the reddish colors. These studies demonstrate the level of molecular complexity synthesized of GCR processing hydrocarbon and hint at the role played by irradiated ice in the early production of biological precursor molecules.

中文翻译：

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银河宇宙射线对甲烷和乙炔冰的处理及其对柯伊伯带天体颜色多样性的影响

柯伊伯带天体表现出比任何其他太阳系群体更广泛的颜色范围。这种颜色多样性的起源尚不清楚，但很可能是银河宇宙射线（GCR）长时间照射有机材料的结果。在这里，我们将超高真空辐照实验与综合光谱分析相结合，检查在柯伊伯带条件下 GCR 处理甲烷和乙炔过程中的颜色演变。这项研究复制了柯伊伯带天体群的颜色，例如鸟神星、奥喀斯星和萨拉西亚星。带有多达三个环的芳香族结构单元，如菲 (C14H10), 苯酚 (C9H10) 和苊 (C12H8），其中一些带有通过不饱和接头连接的 DNA 和 RNA 的结构基序，被发现在产生微红色的过程中发挥着关键作用。这些研究证明了 GCR 加工碳氢化合物的分子复杂性水平，并暗示了辐照冰在生物前体分子的早期生产中所发挥的作用。