Carbon-grain Sublimation: A New Top-down Component of Protostellar Chemistry
Carbon-grain Sublimation: A New Top-down Component of Protostellar Chemistry
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DOI：
10.3847/2041-8213/ab9f97
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发表时间：
2020-06
期刊：
影响因子：
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通讯作者：
M. L. R. van ’t Hoff;E. Bergin;J. Jørgensen;G. Blake
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文献类型：
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作者：
M. L. R. van ’t Hoff;E. Bergin;J. Jørgensen;G. Blake
地球的碳赤字一直是我们理解太阳系形成的一个持续问题。一个可能的解决方案是在行星形成过程的早期，碳颗粒在所谓的烟灰线（10300 K）处升华。在这里，我们认为，这个过程中最有可能的签名是过量的碳氢化合物和腈内的烟灰线，和更高的激发温度为这些分子相比，含氧的复杂的有机物，解吸周围的水雪线（100 K）。这种特征在文献中已有报道，例如在猎户座KL中，虽然不是统一的，可能是由于不同研究的观测环境和分析方法的差异或原恒星吸积的偶发性。如果这一过程是活跃的，这将意味着在原恒星阶段，碳化学中存在一种迄今未知的成分，这种成分是自上而下从较大物种的毁灭开始，而不是自下而上从原子开始。在这样一个自上而下的组件的存在下，有机分子的起源需要重新探索。
Earth’s carbon deficit has been an persistent problem in our understanding of the formation of our solar system. A possible solution would be the sublimation of carbon grains at the so-called soot line (∼300 K) early in the planet-formation process. Here, we argue that the most likely signatures of this process are an excess of hydrocarbons and nitriles inside the soot line, and a higher excitation temperature for these molecules compared to oxygen-bearing complex organics that desorb around the water snowline (∼100 K). Such characteristics have been reported in the literature, for example, in Orion KL, although not uniformly, potentially due to differences in the observational settings and analysis methods of different studies or the episodic nature of protostellar accretion. If this process is active, this would mean that there is a heretofore unknown component to the carbon chemistry during the protostellar phase that is acting from the top down—starting from the destruction of larger species—instead of from the bottom up from atoms. In the presence of such a top-down component, the origin of organic molecules needs to be re-explored.