Comets are frozen remnants of our solar system’s formation, and comparing their chemical composition to that of planet-forming systems can reveal crucial insights about our origins, potentially answering one of the most challenging questions in planetary science, i.e., whether cometary material was mainly inherited from the protosolar nebula or reprocessed during the solar system formation. Here we provide the first statistical analysis of methanol, formaldehyde, and ammonia abundances in 35 comets and 11 protostellar solar analogs and planet-forming disks. We show that comets from different dynamical families have comparable compositions on average, implying that their chemistry is preserved even after formation. While abundances retrieved from infrared and (sub)millimeter ground-based observations are in agreement, there are significant differences with those obtained via mass spectroscopy for 67P/Churyumov–Gerasimenko, target of the ESA-Rosetta mission; we discuss the implication of relying solely on the latter data for comparisons with disk abundance ratios. Finally, we find a significant difference in the [CH₃OH]/[H₂CO] ratio in comets observed within or farther than 1 au from the Sun, suggesting that temperature-activated mechanisms can enhance the H₂CO production in the coma; this bias can strongly influence our understanding of comet chemistry in the context of planet formation. When compared to planet-forming systems, the [CH₃OH]/[H₂CO] and [NH₃]/[CH₃OH] molecular abundance ratios in comets are consistent with those measured in Class 0 hot corinos and in the inner regions of Class II disks, hence suggesting an inheritance scenario.

中文翻译：

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彗星和行星形成盘中的冰化学：CH3OH、H2CO 和 NH3 丰度比的统计比较


彗星是太阳系形成过程中的冰冻残余物，将它们的化学成分与行星形成系统的化学成分进行比较可以揭示有关我们起源的重要见解，有可能回答行星科学中最具挑战性的问题之一，即彗星物质是否主要是遗传的来自原太阳星云或在太阳系形成过程中重新加工。在这里，我们首次对 35 颗彗星和 11 个原恒星太阳类似物和行星形成盘中的甲醇、甲醛和氨丰度进行了统计分析。我们表明，来自不同动力学家族的彗星平均成分具有相似性，这意味着即使在形成后，它们的化学成分也得以保留。虽然从红外和（亚）毫米地面观测中检索到的丰度是一致的，但与通过 ESA-Rosetta 任务目标 67P/Churyumov-Gerasimenko 的质谱获得的丰度存在显着差异；我们讨论仅依赖后者数据与盘丰度比进行比较的含义。最后，我们发现在距太阳 1 个天文单位以内或距离太阳较远的地方观测到的彗星中 [CH ₃ OH]/[H ₂ CO] 比率存在显着差异，这表明温度激活机制可以增强彗发中 H ₂ CO 的产生;这种偏见会强烈影响我们对行星形成过程中彗星化学的理解。与行星形成系统相比，彗星中的[CH ₃ OH]/[H ₂ CO]和[NH ₃ ]/[CH ₃ OH]分子丰度比与在0级热科里诺斯和内层测量的一致。 II 类磁盘的区域，因此表明存在继承情况。